EPA 560/4-90-016
July 1990
ESTIMATED WORKER EXPOSURE TO 2378 TCDD AND
2378 TCDF FROM PROCESSING AND COMMERCIAL
USE OF PULP AND PAPER MILL SLUDGE
by
Radha Krishnan, Chris Meyer, Bob Goodman,
Mary Beth Foerst
Contract No. 68-D8-0112
Work Assignment No. P2-2
PN 3786-26
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF TOXIC SUBSTANCES
401 M STREET, S.W.
WASHINGTON, D.C. 20460
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DISCLAIMER
This document has been reviewed and approved for publication by the Office of Toxic
Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency. The
use of trade names or commercial products does not constitute Agency endorsement or
recommendation for use.
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ACKNOWLEDGEMENTS
This report was prepared by PEI Associates, Inc. of Cincinnati, Ohio for the U.S.
Environmental Protection Agency's Office of Toxic Substances (OTS) under EPA Contract No.
68-D8-0112, Work Assignment Nos. Pl-20 and P2-2. The OTS Task Managers, George Heath and
Nhan Nguyen, and Ward Penberthy of OTS provided overall guidance in this effort. The PEI
Program Manager was Tom Corwin, and The Task Manager was Radha Krishnan, P.E. The
principal authors of the report were Radha Krishnan, Bob Goodman, Chris Meyer and Mary Beth
Foerst. The comments provided by the following individuals during the preparation of the report
are gratefully acknowledged: Mike Babich of the Consumer Products Safety Commission (CPSC);
Bob Fisher of the National Council of the Paper Industry for Air and Stream Improvement
(NCASI); 'and Claire Sullivan of the United Paperworkers International Union (UPIU).
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CONTENTS
Page
Figures iii
Tables iii
1. Introduction 1-1
2. Industry Profile 2-1
2.1 Sludge formation, processing, and disposal
operations 2-1
2.2 Dioxins in pulp and paper mill sludges 2-12
2.3 Sludge handling/disposal workforce characterization 2-19
3. Worker Exposure 3-1
3.1 Potential for worker exposure 3-1
3.2 Personal protective equipment and controls 3-73
4. Conclusions and Recommendations 4-1
References R-l
Appendices
A. 10A-Min Study: 2378 TCDD and 2378 TCDF Concentrations
in Sludge A-l
B. Exposed Population and Particulate Matter Emissions
Calculations for Sludge Handling/Processing
Operations B-l
C. Exposed Population and Particulate Matter Emissions
Calculations for Landfill ing Operations C-l
D. Exposed Population and Particulate Matter Emissions
Calculations for Land Application of Sludge D-l
E. Exposed Populations and Particulate Matter Emis-
sions Calculations for Composting Operations E-l
F. Risk Assessment Methodology F-l
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FIGURES
Number Page
2-1 Schematic of Pulp and Paper Mill Sludge Processing and
Disposal Techniques 2-5
TABLES
Number Page
2-1 Sludge Disposal Operations Reported in the 104-Mill
Study 2-6
2-2 Summary of Wastewater Treatment Operations at the
Pulp and Paper Mills Involved in the 5-Mill Study 2-13
2-3 Operational and Sludge Characteristics for the Pulp and
Paper Mills Involved in the 5-Mill Study 2-14
2-4 Concentrations of 2378 TCDD and 2378 TCDF in Various
Sludges (5-Mill Study) 2-16
2-5 Summary of TEQ and Corresponding 2378 TCDD and 2378
TCDF Concentrations in Various Sludges (5-Mill Study) 2-17
2-6 Summary of TEQ and Corresponding 2378 TCDD and 2378
TCDF Concentrations Measured in Combined Dewatered
Sludge (104-Mill Study) 2-20
2-7 Summary of TEQ and Corresponding 2378 TCDD and 2378
TCDF Concentrations Measured in Non-dewatered
Sludge (104-Mill Study) 2-20
3-1 Mass Balance Models 3-6
3-2 Estimated Inhalation Exposure to 2378 TCDD and 2378 TCDF
for Waste Treatment Plant Operators and Haulers/Front-
End Loader Operators From Volatilization 3-10
3-3 Estimated Toxicity Equivalents and Percent Exposure Due
to 2378 TCDD for Waste Treatment Plant Operators and
Haulers/Front-End Operators From Volatilization 3-13
(continued)
iii
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TABLES (continued)
Number
3-4 Assumptions and Uncertainties in Variables for Calculating
Lifetime Average Daily TEQ From Daily TEQ 3-15
3-5 Assumptions and Uncertainties in Estimating Inhalation
Exposure to 2378 TCDD and 2378 TCDF for Waste Treatment
Plant Operators and Haulers/Front-End Loader Operators
From Volatilization 3-16
3-6 Estimated Inhalation Exposure to 2378 TCDD and 2378 TCDF
for Waste Treatment Plant Operators and Haulers/Front-
End Loader Operators From Particulate Matter 3-21
3-7 Estimated Toxicity Equivalents and Percent Exposure Due to
2378 TCDD for Waste Treatment Plant Operators and
Haulers/Front-End Operators From Particulate Matter 3-2?
3-8 Estimated Dermal Exposure to 2378 TCDD and 2378 TCDF for
Waste Treatment Plant Operators and Haulers/Front-
End Loader Operators 3-26
3-9 Estimated Toxicity Equivalents and Percent Exposure Due
to 2378 TCDD for Waste Treatment Plant Operators and
Haulers/Front-End Operators From Dermal Exposure 3-28
3-10 Assumptions and Uncertainties in Estimating Dermal
Exposure to 2378 TCDD and 2378 TCDF for Waste
Treatment Plant Operators and Haulers/Front-End
Loader Operators 3-29
3-11 Estimated Inhalation Exposure to 2378 TCDD and 2378 TCDF
for Landfill Equipment Operators From Volatilization 3-34
3-12 Estimated Toxicity Equivalents and Percent Exposure Due to
2378 TCDD for Landfill Equipment Operators From
Volatilization 3-36
3-13 Assumptions and Uncertainties in Estimating Inhalation
Exposure to 2378 TCDD and 2378 TCDF for Landfill
Equipment Operators From Volatilization 3-36
3-14 Estimated Inhalation Exposure to 2378 TCDD and 2378 TCDF
for Landfill Equipment Operators From Particulate
Matter 3-37
(continued)
iv
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TABLES (continued)
Number Page
3-15 Estimated Toxicity Equivalents and Percent Exposure Due
to 2378 TCDD for Landfill Equipment Operators From
Particulate Matter 3-37
3-16 Estimated Dermal Exposure to 2378 TCDD and 2378 TCDF for
Landfill Equipment Operators 3-39
3-17 Estimated Toxicity Equivalents and Percent Exposure Due
to 2378 TCDD for Landfill Equipment Operators From
Dermal Exposure 3-40
3-18 Assumptions and Uncertainties in Estimating Dermal
Exposure to 2378 TCDD and 2378 TCDF for Landfill
Equipment Operators 3-41
3-19 Estimated Inhalation Exposure to 2378 TCDD and 2378 TCDF
for Land Application Equipment Operators From Vola-
tilization 3-45
3-20 Estimated Toxicity Equivalents and Percent Exposure Due to
2378 TCDD for Land Application Equipment Operators From
Volatilization 3-47
3-21 Assumptions and Uncertainties in Estimating Inhalation
Exposure to 2378 TCDD and 2378 TCDF for Land
Application Equipment Operators From Volatilization 3-48
3-22 Estimated Inhalation Exposure to 2378 TCDD and 2378 TCDF
for Land Application Equipment Operators From Par-
ticulate Matter 3-49
3-23 Estimated Toxicity Equivalents and Percent Exposure Due to
2378 TCDD for Land Application Equipment Operators From
Particulate Matter 3-50
3-24 Estimated Dermal Exposure to 2378 TCDD and 2378 TCDF
for Land Application Equipment Operators 3-52
3-25 Estimated Toxicity Equivalents and Percent Exposure Due to
2378 TCDD for Land Application Equipment Operators From
Dermal Exposure 3-53
3-26 Assumptions and Uncertainties in Estimating Dermal
Exposure to 2378 TCDD and 2378 TCDF for Land
Application Equipment Operators 3-54
(continued)
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TABLES (continued)
Number Page
3-27 Estimated Inhalation Exposure to 2378 TCDD and 2378 TCDF
for Composting Operation Workers From Volatilization 3-60
3-28 Estimated Toxicity Equivalents and Percent Exposure to
2378 TCDD for Composting Operation Workers From
Volatilization 3-63
3-29 Assumptions and Uncertainties in Estimating Inhalation
. Exposure to 2378 TCDD and 2378 TCDF for Composting
Operation Workers From Volatilization 3-64
3-30 Estimated Inhalation Exposure to 2378 TCDD and 2378 TCDF
for Composting Operation Workers From Participate
Matter 3-66
3-31 Estimated Toxicity Equivalents and Percent Exposure Due
to 2378 TCDD for Composting Operation Workers From
Particulate Matter 3-67
3-32 Estimated Dermal Exposure to 2378 TCDD and 2378 TCDF
for Composting Operation Workers 3-69
3-33 Estimated Toxicity Equivalents and Percent Exposure Due
to 2378 TCDD for Composting Operation Workers From
Dermal Exposure 3-70
3-34 Assumptions and Uncertainties in Estimating Dermal
Exposure to 2378 TCDD and 2378 TCDF for Composting
Operation Workers 3-71
4-1 Summary of 2378 TCDD and 2378 TCDF Daily Inhalation and
Dermal Exposure Estimates for Workers Involved in
Processing and Commerical Usage of Pulp and Paper Mill
Sludge 4-4
4-2 Summary of Daily Toxicity Equivalents, Lifetime Average
Daily Toxicity Equivalents, and Percentage Exposure Due
to 2378 TCDD for Workers Involved in Processing and
Commercial Usage of Pulp and Paper Mill Sludge 4-6
4-3 Summary of Average and Population Risks Based on Lifetime
Average Daily Toxicity Equivalents For Workers Involved
in Processing and Commercial Usage of Pulp and Paper
Mill Sludge 4-8
F-l Variables for Estimating Average Risks and Population
Risks F-4
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SECTION 1
INTRODUCTION
Various isomers of polychlorinated dibenzodioxins (PCDDs) and polychlo-
rinated dibenzofurans (PCDFs) have been found to be formed during bleaching
of wood pulp with chlorine or chlorine-based bleaching chemicals. Quantita-
tive studies conducted by the U.S. Environmental Protection Agency (EPA) and
the paper industry have shown that PCDDs and PCDFs may be retained in low
levels in bleached pulp, crude paper products (e.g., unconverted paper,
paperboard, fibers), and finished commercial and consumer grade pulp-/paper-
based products. Furthermore, PCDDs and PCDFs may also be retained in waste-
water and sludge generated during the manufacture of these products and
possibly be released to ambient air.
On July 27, 1988, the EPA entered into a Consent Agreement with the
Environmental Defense Fund and National Wildlife Federation regarding a
schedule for review of PCDDs and PCDFs from pulp and paper mills. In re-
sponse to the Consent Decree, EPA is preparing risk assessments for PCDDs and
PCDFs from pulp and paper mill products and wastes in order to determine
what, if any, control actions are necessary.
The purpose of this report is to aid OTS in its assessment of worker
exposure to PCDDs and PCDFs during the processing and commercial use of
sludge generated from wastewater treatment operations in pulp and paper
mills.
1-1
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This report is organized into four sections. This section (Section 1)
provides the background and purpose of the study. Section 2 provides a
profile of industrial processes and operations that may result in exposure to
PCDDs and PCDFs during the processing and commercial use of pulp and paper
mill sludges. It summarizes the results of the 5-Mill and 104-Mill studies
(which are discussed in detail in Sections 2.2.1 and 2.2.2) and includes a
workforce characterization for different operations involving the processing
and commercial use of pulp and paper mill sludge. Section 3 discusses the
potential for dermal and inhalation exposure to specific PCDDs and PCDFs for
the processes/operations discussed in Section 2. It includes engineering
estimates of the levels of inhalation and dermal exposure for workers in-
volved in different operations. Section 4 presents the conclusions and
recommendations of this study, including a summary of 2,3,7,8-tetrachloro-
dibenzo-p-dioxin (2378 TCDD) and 2,3,7,8-tetrachlorodibenzofuran (2378 TCDF)
daily exposure, toxicity equivalent (TEQ) daily exposures and lifetime
average daily exposures, and average and population risks for workers in-
volved in the processing and commercial use of pulp and paper mill sludge.
Appendix A presents 2378 TCDD and 2378 TCDF concentrations for sludge on a
dry basis as reported in the 104-Mill Study. Appendices B through E present
the methodologies for estimating the exposed population and particulate
matter emission rates for sludge handling/ processing operations, landfilling
operations, land application operations, and composting operations, respec-
tively. Appendix F presents the methodology employed in this report to
calculate average and population risks.
1-2
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SECTION 2
INDUSTRY PROFILE
This section discusses wastewater sludge formation, processing, and
disposal operations in pulp and paper mills that may result in worker expo-
sure to PCDDs and PCDFs. Quantitative analyses of the sludge are presented
for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2378 TCDD) and 2,3,7,8-tetrachloro-
dibenzofuran (2378 TCDF) from the 5-Mill and the 104-Mill studies which are
described later in this section. In addition, a workforce characterization
is presented for sludge formation, processing, and disposal operations.
2.1 SLUDGE FORMATION, PROCESSING, AND DISPOSAL OPERATIONS
There are limited data available in the literature to characterize typi-
cal sludge formation, processing, and disposal operations at pulp and paper
mills. For the most part, pulp and paper mills process and dispose of their
sludge much in the same manner as municipal wastewater treatment facilities,
using dewatering to reduce sludge volume followed by disposal via landfill-
ing, land application, or composting. Consequently, parallels were drawn be-
tween municipal wastewater sludge treatment and disposal operations and those
of pulp and paper mills. This section describes sludge formation, process-
ing, and disposal operations which may be employed at pulp and paper mills.
2.1.1 Sludge Formation and Processing
Two kinds of sludge are generated by wastewater treatment at pulp and
paper mills: primary and secondary sludge. Typical wastewater treatment
2-1
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operations at pulp and paper mills include primary clarification, aerobic
suspended-growth treatment processes, and secondary clarification. Primary
clarification results in the formation of primary sludge by gravity settling
of heavy suspended solids. Aerobic suspended-growth treatment processes
include activated sludge processes, aeration basins, aerated lagoons, and
aerobic stabilization ponds in which nonsettleable colloidal solids are
coagulated and organic matter is stabilized by biological treatment.
Secondary clarification results in the formation of secondary sludge by
gravity settling of biological solids.
Primary sludges consist of solids which are lost from the pulp and paper
manufacturing process and are subsequently removed by primary clarification
(Ledbetter 1976). These solids are composed of fibers, clay filler mate-
rials, coating clays, and other chemical additives (Kirk-Othmer 1981). In
addition to fibers, other organic components such as wood dust, fiber debris,
ray cells, starches, dextrine, resins, and protein may be present. Solids
losses in primary sludges from most categories of paper manufacture represent
2 to 4 percent of production. Typical water contents of non-dewatered pri-
mary sludges from pulp and paper manufacturing operations may range from 90
to 98 percent (Ledbetter 1976).
Secondary sludges are largely biological in nature and are harder to
handle and dewater (Kirk-Othmer 1981). Secondary sludge water contents may
range from 98 to 99.5 percent (Hammer 1975).
The primary and secondary sludges must be processed for volume reduction
prior to disposal. Processing techniques which involve sludge volume reduc-
tion include thickening, conditioning, and dewatering (Kirk-Othmer 1981).
2-2
-------
Thickening is primarily accomplished using either gravity settling, which is
applied to mixtures of primary and secondary sludges, or dissolved air flota-
tion which is usually applied to secondary sludges only. Thickening will in-
crease solids content on an average to 5 percent (Hammer 1975). Conditioning
is performed to improve the sludge dewatering characteristics. Chemicals
such as ferric chloride, lime, alum, and organic polymers are added prior to
dewatering to coagulate solids, resulting in release of absorbed water. De-
watering -is accomplished using centrifugation, vacuum filtration, or pressure
filtration. Solids content may be increased to 20 to 45 percent by centri-
fugation, vacuum filtration and pressure filtration (Metcalf & Eddy 1979).
Dewatering may be performed on the primary and secondary sludges individually
or on a mixture of both. The dewatered sludge cake is discharged on to a
conveyor belt and proceeds to disposal operations (Hawks 1989).
No data are available in the literature to characterize the typical unit
operations at the wastewater treatment facilities of pulp and paper mills.
The vast majority employ primary treatment and some form of secondary treat-
ment along with dewatering of sludges from these operations.
The mechanism by which contamination from PCDDs and PCDFs occurs in pulp
and paper mill sludges is currently being investigated by the industry.
PCDDs and PCDFs are known to be formed during chlorine or chlorine derivative
bleaching operations employed in pulp mills, and may be present in bleach
plant and paper machine wastewater. The PCDDs and PCDFs have a strong affin-
ity for organic matter, and binding with organic matter in primary and second-
ary sludge may occur (Olson 1988).
2.1.2 Sludge Disposal Operations
Sludge from pulp and paper mills is disposed in a manner similar to that
2-3
-------
used for municipal sewage sludge. Figure 2-1 presents a schematic of various
pulp and paper mill sludge processing and disposal techniques. Disposal
methods include landfilling, incineration, surface impoundments, land applica-
tion, and distribution as a salable product (e.g., fertilizers, soil condi-
tioners). Some of the disposal techniques (e.g., incineration, landfilling)
may be conducted on-site or off-site. Table 2-1 presents the disposal
operations used at mills involved in the 104-Mill Study (described later in
Section 2.2.2), as well as total and average sludge production by disposal
operation. Table 2-1 shows that landfilling is the predominant disposal
operation of choice currently in industry, although a number of mills are
also using incineration and surface impoundments. Sixteen of the 104 mills
employed more than one type of sludge disposal operation. For the purpose of
determining sludge production values by disposal operation, the amount of
sludge production at each of these 16 facilities was not disaggregated, but
rather was assigned to each disposal operation employed.
2.1.2.1 Landfilling
Landfilling involves the disposal of sludge in company-owned, publicly-
owned, or privately-owned landfills. In this disposal operation, sludge is
almost universally dewatered to a solids content of 20 to 25 percent to
reduce its volume and lower transportation costs (EPA 1979). Typically the
dewatered sludge is transferred from the dewatering operations to storage or
directly to heavy duty dump trucks. If storage operations are used, the
dewatered sludge will be loaded into dump trucks by a front-end loader
(Ledbetter 1976). The dewatered sludge is hauled to the landfill where the
basic operations involve spreading, compacting, and covering the sludge with
excavated soil daily (Hammer 1975).
2-4
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The type and number of equipment used in landfill ing operations depend
on the landfill design methods and dimensions as well as sludge quantity.
Landfill design methods include the trench and area fill methods, and (in the
case of disposal in a publicly or privately-owned landfill) the codisposal
method. The trench method will involve the use of trenching machines, back-
hoes with a loader, track dozers, and excavators. Two or more trench
machines will be used to landfill sludge quantities in excess of 500 wet tons
per day (as compared to one or ione for smaller operations); a track loader,
track dozer, backhoe with a loader, and excavator may or may not be used.
The area fill method will involve the use of backhoes with a loader, track
loaders, wheel loaders, track dozers, scrapers, and draglines. Two or more
track dozers will be used to landfill sludge quantities in excess of 500 wet
tons per day (as compared to one or none for smaller operations); a scraper,
track loader, wheel loader, and backhoe with a loader may or may not be used.
The codisposal method will involve the use of track loaders, track dozers,
tractors with discs, and graders. Two or more track loaders and tractors
with discs will be used to landfill sludge quantities in excess of 500 wet
tons per day (as compared to one or none for smaller operations); a track
dozer and grader may or may not be used. The total pieces of equipment used
will range between 1 and 5 and may even be greater in the case of large
quantities of sludge (EPA 1979).
The majority of landfill ing operations occur on land owned by the pulp
and paper mills. According to the 104-Mill Study data, 22 mills use on-site
landfilling for disposal of sludges, 32 mills use off-site landfills of which
20 are owned by the mill, and the location of landfills for 6 mills was not
2-7
-------
reported. The landfills may also receive bottom and fly ash from sludge
incineration, that may be contaminated with PCDDs and PCDFs.
2.1.2.2 Incineration--
Incineration is a two-step oxidation process involving drying of the
sludge followed by combustion. This process may occur in separate pieces of
equipment or successively in a single unit (EPA 1979). Prior to incinera-
tion, the sludge is dewatered in a centrifuge, vacuum filter, or pressure
filter to a solids content of at least 30 percent. The dewatered sludge
proceeds directly to incineration by means of conveyors. Incineration con-
verts the sludge into an inert ash which is handled in wet or dry form (Han-
mer 1975). In wet form, the ash is slurried with scrubber water and is
pumped to an ash lagoon. In dry form, the ash is conveyed mechanically by a
bucket elevator to a storage hopper for discharge into a dump truck for
eventual disposal in a landfill (Metcalf & Eddy 1979).
According to the 104-Mill Study data,, all mills that practice sludge
incineration burn the sludge in waste fuel- or combination-power boilers. In
the case of waste fuel-power boilers, sludge is mixed with wood waste, which
may consist of bark, knots, and/or sawdust, and is burned to produce steam.
In combination-power boilers, the sludge or a mixture of sludge and wood
waste may be mixed with coal, oil, or natural gas and burned to produce
steam.
A current study by the National Council of the Paper Industry for Air and
Stream Improvement, Inc. (NCASI) has found measurable PCDD and PCDF concentra-
tions in bottom ash and fly ash from incineration of sludge in power boilers.
Even though detectable PCDD and PCDF concentrations were found in the residual
2-8
-------
ash, a substantial reduction of the PCDDs and PCDFs in the sludge was attained
in the incineration process (Fisher 1989). The quantity of ash produced is
also much smaller compared to the sludge. Exposure to PCDDs and PCDFs associ-
ated with incineration is not addressed in this report. These exposures are
the topic of a report being developed by EPA's Office of Air Quality and
Planning Standards (OAQPS).
2.1.2.3 Surface Impoundments--
Surface impoundments or "sludge ponds" are excavations or areas enclosed
by dikes for the purpose of retaining sludge. According to the 104-Mill
Study data, nondewatered sludge is pumped directly from clarifiers to on-site
sludge ponds, and primary sludge (versus secondary sludge) is chiefly dis-
posed in the sludge ponds. One facility dewaters its sludge and then trans-
fers its sludge to an off-site surface pond by barge.
2.1.2.4 Land Application--
Land application involves disposal of sludge by surface spreading or
subsurface injection, usually on agricultural lands. Dewatered sludge is
usually applied to land by a conventional fertilizer or manure spreader.
Liquid sludges are surface spread by tank truck or injected below the surface
(Metcalf & Eddy 1979). Surface spreading may require movement and burying of
the sludge below the soil by plows, graders, or bulldozers (EPA 1979).
According to the 104-Mill Study data, only one of the seven facilities
utilizes on-site disposal of sludge by land application. Two facilities
landspread the sludge as fertilizer on company-owned pine tree plantations.
One company disposes its sludge in abandoned coal mine reclamation projects
2-9
-------
where the sludge is either deep-filled into the coal mines or used as surface
topdressing. The other three facilities utilize off-site disposal of sludge
by land application.
2.1.2.5 Distribution of Sludge as a Salable Product--
Sludge is processed for distribution as a salable product by heat-drying
or composting techniques. The sludge is usually dewatered prior to process-
ing to reduce the water content (EPA 1979).
Heat-drying is employed to remove moisture from sludge so that it can be
efficiently processed into fertilizer. Heat-drying is also employed prior to
incineration to ensure proper combustion of the sludge. The drying of the
sludge is necessary in fertilizer manufacturing to permit grinding of the
dried sludge. Drying is accomplished by flash spray, rotary, or multiple
hearth dryers which will reduce the moisture content of the sludge to less
than 10 percent (Metcalf & Eddy 1979).
Composting is undertaken to biologically degrade the sludge into a
stable end product which is used as a soil conditioner. The composting
process involves three steps: 1) preparation of the wastes to be composted,
2) decomposition of the prepared wastes, and 3) preparation and marketing of
the product. The preparation step may include addition of wood chips or bark
as bulking agents for moisture and porosity control and addition of organic
nutrients such as sawdust. The decomposition step is accomplished using
windrow or aerated pile techniques. In windrow composting, prepared sludge
is placed in windrows in open fields and is frequently mixed and turned by
mobile equipment to maintain aerobic conditions (Metcalf & Eddy 1979). The
windrow is turned two or three times daily for the first five days and then
2-10
-------
turned daily for thirty days (EPA 1979). The composted material is then
cured for an additional two to four weeks (Metcalf & Eddy 1979). If bulking
agents are used, the cured compost is screened and the bulking agents recy-
cled. In aerated pile composting,-aeration is induced by forced air circu-
lation (EPA 1979). Composted material is removed, screened, and finally
cured for an additional period of three to four weeks. Final product prepara-
tion of compost from the windrow or aerated pile techniques may involve fine
grinding, blending with various additives, granulating, bagging, storing, and
shipping (Metcalf & Eddy 1979).
The type and number of pieces of equipment used in these operations
depends on the composting technique employed and the size and location of the
operations. Front-end loaders are used to load dewatered sludge into dump
trucks and for initial preparation and placement of the sludge. Mixing
machines are used to turn windrows to ensure aeration. Rotary or vibrating
screens are used to remove bulking agents, namely wood chips, for reuse (EPA
1979). Additional equipment may be required if the compost is ground,
blended, or further processed in some manner prior to distribution.
According to the 104-Mill Study data, only one of the seven facilities
which distribute sludge as a salable product practices flash drying of sludge
for use as a fertilizer ingredient. One facility sells the sludge to an
outside contractor who converts it into insulation or hydromulch. Three
facilities send their sludge off-site for composting. One facility composts
the sludge with paunch manure from an adjacent meat processing plant and,
after composting is complete, disposes the sludge in an on-site landfill.
The site of composting operations at one facility could not be determined.
2-11
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2.2 DIOXINS IN PULP AND PAPER MILL SLUDGES
Sampling of sludge from pulp and paper mills that produce and/or process
bleached pulp and bleached pulp-based products has shown that two PCDD and
PCDF isomers, 2378 TCDD and 2378 TCDF, are predominantly present in primary
and secondary sludges formed during wastewater treatment operations.
In an attempt to quantify concentrations of 2378 TCDD and ?378 TCDF pro-
duced during pulp and paper manufacturing operations, several recent studies
have been- undertaken by the U.S. EPA and the paper industry. These studies
include the Cooperative Dioxin Screening Study (or 5-Mill Study), the 104-
Mill Study, and the 25 Bleach Line Study. Results have been published for
the 5-Mill Study and 104-Mill Study; however, the results of the 25 Bleach
Line Study, which is sponsored by the paper industry, will not be available
until the end of 1989 (Bond 1989). All of these studies involve the measure-
ment of 2378 TCDD and 2378 TCDF dioxin concentrations in sludge on a dry
basis as well as in pulp and wastewater effluent.
2.2.1 The 5-Mill Study
The 5-Mill Study was conducted from June 1986 to January 1987 at five
bleached Kraft pulp and paper mills. These mills were identified in the
study as Mills A, B, C, D, and E. Mill A has a wastewater treatment system
consisting of primary clarification, an activated sludge process, and second-
ary clarification. Primary and secondary sludges are combined and dewatered
by pressure filtration prior to landfill disposal. The wastewater treatment
system of Mill B consists of primary clarification, a holding pond, an aera-
tion pond, and secondary clarification in two tanks. Primary and secondary
sludges are dewatered separately and secondary sludge undergoes conditioning
2-12
-------
prior to dewatering. Primary sludges are landfilled on-site, whereas second-
ary sludges are landfilled off-site. The wastewater treatment system of Mill
C consists of primary clarification, an aerated stabilization basin, an acti-
vated sludge process, and secondary clarification in two tanks. Secondary
sludge is thickened and combined with primary sludge prior to dewatering.
The dewatered sludge is either processed for commercial use or is landfilled.
The wastewater treatment system of Mill D consists of primary clarification
in two tanks, an activated sludge process, dissolved air flotation for sec-
ondary sludge thickening, and secondary clarification in two tanks. The
primary and secondary sludges are combined, dewatered, and sent to a landfill
for disposal. The wastewater treatment system of Mill E consists of primary
clarification, an aeration lagoon, and secondary clarification. Secondary
sludge is gravity thickened prior to dewatering with the primary sludge on
sludge presses (EPA 1988a). Table 2-2 summarizes the wastewater treatment
operations at the five mills. Table 2-3 presents operational and sludge
characteristics for the pulp and paper mills in the 5-Mill Study.
TABLE 2-2. SUMMARY OF WASTEWATER TREATMENT OPERATIONS AT THE PULP
AND PAPER MILLS INVOLVED IN THE 5-MILL STUDY
Process operation
Primary clarification
Holding pond/aerated stabilization basin
Aeration pond/lagoon
Activated sludge
Secondary clarification
Condition ing/ thicken ing
Dewatering
Landfill ing of sludge
Commercial use of sludge
A
X
X
X
X
X
B
X
X
X
X
X
X
X
Mill
C
X
X
X
X
X
X
X
X
D
X
X
X
X
X
X
E
X
X
X
X
X
2-13
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2-14
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Table 2-4 presents individual concentrations of 2378 TCDD and 2378 TCDF,
in various sludges from the five mills. The table shows that 2378 TCDD and
2378 TCDF concentrations are much higher in secondary sludges as compared to
primary and combined dewatered sludges. Combined dewatered sludges, which
are a mixture of secondary and primary sludge, have higher 2378 TCDD and 2378
TCDF concentrations than primary sludges. Concentrations of 2378 TCDD anc1
2378 TCDF may be higher in secondary sludges as compared to primary sludges
because secondary solids are comprised of organic biological solids for which
PCDDs and PCDFs have an affinity.
Table 2-5 presents a summary of the range of concentrations for toxicity
equivalents (TEQ) and the corresponding range of 2378 TCDD and 2378 TCDF
concentrations in various sludges from the five mills. The TEQ values reflect
the relative toxicity of 2378 TCDF with respect to 2378 TCDD. Equation 1 is
used to calculate TEQ while Equation 2 is used for calculating percent con-
tribution due to TCDD.
TEQ = CTCD[) + (0.1) CTC[)F Equation 1
%TCDD =, - x 100
LTCDD
Where:
TEQ = toxicity equivalent, ppt
Cjrnn = concentration of 2378 TCDD in sludge, ppt
CTCDF = concentration of 2378 TCDF in sludge, ppt
%TCDD = percent contribution due to 2378 TCDD, percent
The low and high plant TEQs provide the data points for the lower and upper
range of 2378 TCDD and 2378 TCDF concentrations used for exposure and risk
assessment estimates in this report. It must be noted, however, that the
range of concentrations presented in Table 2-5 may not necessarily be
representative of all pulp and paper mills.
2.2.2 The 104-Mill Study
The 104-Mill Study was conducted from April 1988 to August 1989 at 104
2-15
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TABLE 2-4. CONCENTRATIONS OF 2378 TCDD AND 2378 TCDF IN
VARIOUS SLUDGES (5-MILL STUDY)3
(ppt)
Mm A
Primary sludge
Secondary sludge
Combined dewatered sludge
Mill B
Primary sludge .
Secondary sludge
Mill C
Secondary sludge
Combined dewatered sludge
Mill D
Primary sludge
Secondary sludge
Combined dewatered sludge
Mill E
Secondary sludge
Combined dewatered sludge
2378 TCDD
24
710
37
19
89
11
3.3
17
36
18
500
180
2378 TCDF
380
10,900
680
100
810
75
39
32
78
34
2100
760
3 EPA 1988a. Concentrations reported on a dry basis,
Secondary sludge sampled before conditioning.
2-16
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TABLE 2-5. SUMMARY OF TEQ AND CORRESPONDING 2378 TCDD and 2378 TCDF
CONCENTRATIONS IN VARIOUS SLUDGES (5-MILL STUDY)9, ppt
Sludge type
Primary
Secondary
Combined
dewatered
TEQ
No. of Samples Range
3 20.2(35)-62(6)
5 18.5(13)-1800(6)
4 7.2(8)-256(19)
2378 TCDD
Range
17-24
11-710
3.3-180
2378 TCDF
Range
32-380
75-10,900
39-760
EPA 1988a. Concentrations reported on a dry basis. Mean and median con-
centrations may not necessarily be representative of all pulp and paper
mills.
Values in parentheses are percent contribution due to 2378 TCDD.
2-17
-------
domestic pulp and paper mills using chlorine-based bleaching processes
(chlorine, chlorine dioxide, or hypochlorite) in the manufacture of bleached
chemical pulp. Eighty-seven of the 104 mills used the Kraft (sulfate) pro-
cess while the remaining 17 used the sulfite process (EPA 1989a). In this
study, concentrations of 2378 TCDD and 2378 TCDF were measured in combined
dewatered wastewater sludge and non-dewatered wastewater sludge (as well as
bleached pulp following the final stage of bleaching and treated wastewater
effluent-prior to dilution with cooling water) (UPIU 1989). Appendix A of
this report presents individual 2378 TCDD and 2378 TCDF concentrations on a
dry basis in sludge samples for the 104 mills.
PEI evaluated the reported concentrations of 2378 TCDD and 2378 TCDF in
combined dewatered and non-dewatered sludges. For the purpose of calculating
TEQ, PEI assumed the concentrations of samples in which 2378 TCDD and 2378
TCDF were not detected to be half of the detection level, and samples which
were not quantified were rejected. A value of the detection limit was not
used in the calculations for quantifying nondetected concentrations since by
definition such concentrations are below the detection limit; a value lower
than the sampling limit of detection is therefore appropriate for quantifying
the nondetected measurements. As described by Hornung and Reed (Hornung
1987), there are two methods for calculating this value: nondetected values
may be replaced by one-half the limit of detection for highly-skewed data, or
the limit of detection divided by the square root of two for clustered data.
Since the 2378 TCDD and 2378 TCDF concentration data are highly skewed,
nondetected concentrations were calculated as the limit of detection divided
by 2.
The TEO and corresponding lower and upper range concentrations of 2378
TCDD and 2378 TCDF in combined dewatered sludges and non-dewatered sludges
2-18
-------
are presented in Tables 2-6 and 2-7, respectively. Tables 2-6 and 2-7 show
that the concentrations of 2378 TCDF are greater than those of 2378 TCDD.
These results concur with those of the 5-Mill Study. Comparison of sludge
analyses between the two studies is limited only to combined dewatered sludge
because information on the type of non-dewatered sludge (primary or secondary)
sampled in the 104-Mill Study was not available. Median TEQ in combined
dewatered sludges were 63.2 and 56.5 ppt for the 5-Mill Study and the 104-Mill
Study, respectively, whereas the corresponding mean YEQ were 97.4 and 167.2
ppt, respectively.
It must be noted that concentrations of 2378 TCDD and 2378 TCDF measured
in the various sludges do not necessarily represent worker exposure to these
compounds during sludge handling, processing, and disposal operations.
Worker exposure depends on a variety of conditions (e.g., engineering con-
trols, personal protective equipment, work practices) which are addressed in
Section 3.
2.3 SLUDGE HANDLING/DISPOSAL WORKFORCE CHARACTERIZATION
No previous studies have been conducted specifically on workforce charac-
terization in sludge handling and disposal operations at pulp and paper mills
(Fisher 1989). No data were available in the literature regarding job cate-
gories and activities for workers involved in the formation, processing, or
disposal of pulp and paper mill sludge. PEI hence characterized the work-
force for these operations based on parallels with municipal sewage sludge
handling and disposal operations. The levels of exposure associated with
various worker activities are estimated in Section 3.
2-19
-------
TABLE 2-6. SUMMARY OF TEQ AND CORRESPONDING 2378 TCDD AND 2378 TCDF
CONCENTRATIONS MEASURED IN COMBINED DEWATERED SLUDGE (104-MILL STUDY)3
(ppt)
No. of samples
104C
TEQ
Range
1.0(19)-3100(8)
Mean
167.2
Median
56.5
2378 TCDD
Range
0.7-1390
2378 TCDF
Range
3.0-17,100
a Information furnished by U.S. Environmental Protection Agency, Washington,
D.C., based on 104-Mill survey; updated results provided in computer
diskette form. Concentrations reported on a dry basis.
Values in parenthesis are percent contribution due to 2378 TCDD.
2378 TCDD was not detected in 3 samples at detection levels ranging from
1.4 to 3.0 ppt.
TABLE 2-7. SUMMARY OF TEQ AND CORRESPONDING 2378 TCDD AND 2378 TCDF
CONCENTRATIONS MEASURED IN NON-DEWATERED SLUDGE (104-MILL STUDY)3
(ppq)
No.
of
15
TEQ
samples Range
6.6(50)-5900(24)
Mean
1002.9
Median
281.0
2378 TCDD
Range
6-4500
2378 TCDF
Range
6-14,
000
3 Information furnished by U.S. Environmental Protection Agency, Washington,
D.C., based on 104-Mill survey; updated results provided in computer
diskette form. Concentrations reported on a dry basis.
Values in parentheses are percent contribution due to 2378 TCDD.
2-20
-------
PEI utilized many sources for information on the number of workers
exposed during the handling of pulp and paper mill sludge. These sources
included EPA literature, NIOSH databases, industry data, and discussions with
NCASI and the United Paperworkers International Union (UPIU). Information
pertaining to the range in the number of workers per facility in various job
categories was obtained from EPA literature and discussions with NCASI and
UPIU. In the absence of data, PEI made assumptions such as the number of
workers per facility would be equivalent to the number of pieces of equipment
used during landfilling and land application operations. Assumptions that
were used to estimate the exposed population in specific job categories are
detailed in Appendices B through E.
2.3.1 Sludge Formation and Processing Operations
Three job categories of workers are postulated for the sludge formation
and processing operations: waste treatment plant operators, sludge haulers,
and front-end loader operators.
The wastewater treatment plants at pulp and paper mills operate 24 hours
a day with 3 shifts on-duty and one off-duty, similar to the mill operation
(Sullivan 1989). Waste treatment operations involving the formation of
sludge and sludge processing techniques such as thickening, conditioning, and
dewatering may require as many as five operators per shift to as few as one
or two per shift (Fisher 1989). Sludge processing techniques generally do
not have workers dedicated exclusively to them but rather are handled by
waste treatment plant operators or maintenance staff. These personnel are
dedicated to waste treatment operations. A large staff is generally not
required because the waste treatment plant and sludge processing operations
are fully automated (Hawks 1989).
2-21
-------
Typical waste treatment operator activities will include sludge sam-
pling, maintenance, and cleanup. Samples of dewatered sludge are usually
taken once per shift to determine if the dewatering equipment is operating
properly. Samples of sludge prior to dewatering may also be taken to deter-
mine if the primary and secondary treatment operations are achieving their
designed functions (Fisher 1989). Operators may take readings from gauges or
various pieces of equipment. The waste treatment operator may perform repairs
on dewatering equipment, pumps, conveyors, and other miscellaneous equipment.
The operator is responsible for cleanup of the waste treatment facility
including cleanup of wet sludge or dewatered sludge which has fallen off
conveyors, or cleanup of equipment prior to maintenance.
The waste treatment operator population potentially exposed to PCDDs and
PCDFs is estimated to be approximately 1300 workers. This estimate is based
on the assumption that there are an average of three operators on each of the
four shifts within the 104 mills. The use of four shifts to estimate worker
population represents worst case conditions; however, four shifts are
typically used in the operation of the wastewater treatment plants.
Sludge processing operations will involve preparation of the waste
sludge for disposal. In most cases, the sludge is loaded into dump trucks by
conveyors or a front-end loader and is hauled away for disposal. The number
of employees per shift required for truck loading operations could be as few
as one per shift (sludge hauler) in the case of sludge directly conveyed to
the dump truck, or two per shift (sludge hauler and front-end loader opera-
tor) in the case of sludge conveyed on to a pile. The number of shifts for
the sludge haulers and front-end loader operators is generally two, as this
is the number of shifts used in landfill ing operations.
2-22
-------
Typical activities of sludge haulers and front-end loader operators will
center around their respective equipment. Front-end loader operators will
operate, maintain, and clean their equipment, if necessary. The front-end
loader operator drives the front-end loader and transfers sludge from storage
piles into dump trucks. The sludge hauler drives the dump truck and may
maintain and clean it if necessary. The sludge hauler will transport the
sludge to the disposal site.
The sludge hauler and front-end loader operator population exposed to
PCDDs and PCDFs is estimated to be approximately 400 workers. This estimate
is based on the assumption that there is one hauler and one front-end loader
operator per shift on two shifts within the 104 mills. The use of both a
sludge hauler and front-end loader operator to determine work force
population represents worst-case conditions. Some plants may only employ a
sludge hauler; however, the extent of this occurrence in the industry is
unknown. Two shifts were assumed because disposal operations are generally
not conducted during the night, and landfill operations are conducted on two
shifts.
2.3.2 Sludge Disposal Operations
The number of workers involved with sludge disposal operations depends
on the specific disposal technique applied by the facility, the quantity of
sludge disposed and the location of final disposal.
2.3.2.1 Landfilling Operations--
Landfilling operations may involve pulp and paper mill employees if
sludge is landfilled on company-owned land, or employees of waste disposal
firms if the sludge is landfilled at a site not affiliated with the pulp and
2-23
-------
paper mill. These employees are dedicated to sludge disposal operations
only. Landfill ing operations are usually done in two shifts (Sullivan 1989).
Only one job category of workers is postulated for landfilling operations:
equipment operators.
At the landfill site, the number of equipment operators depends on the
landfill technique selection and quantity of sludge to be disposed. The
total pieces of equipment may range between one and five and may even be
greater in the case of large quantities of sludge (EPA 1979). Thus, the
number of equipment operators per shift may range from one to five, depending
on whether one operator is exclusively dedicated to one piece of equipment.
Typical activities of landfill equipment operators will center around
their equipment. The landfill equipment operators will drive the equipment
which is used to spread, compact, and bury the sludge. These activities may
include maintenance and cleanup of the equipment as well.
The landfill equipment operator population exposed to PCDDs and PCDFs is
estimated to be approximately 400 workers. This estimate is based on the
assumption that there are three equipment operators on each of the two shifts
within the 60 mills which dispose of sludge by landfilling. The number of
equipment operators, derived from the EPA 1979 study, showed that a landfill
operation disposing of 250 wet tons of sludge (which is exactly the average
sludge production for landfilling operations in the 104-Mill Study as shown
in Table 2-1) uses an average of three pieces of equipment. PEI assumed that
each piece of equipment had a dedicated operator. This assumption represents
worst-case conditions as the equipment may not have its own dedicated
operator; however, typically each piece of equipment will have a dedicated
operator.
2-24
-------
2.3.2.2 Incineration--
All of the mills involved in the 104-Mill Study which incinerate sludge
do so on-site, and thus sludge incineration operations will involve only pulp
and paper mill employees. Disposal of residual bottom ash and fly ash,
however, will also involve landfilling personnel as previously described.
Sludge is typically burned with wood waste and fuel in power boilers for
energy recovery. Thus, incineration of sludge and subsequent disposal of
bottom ash and fly ash will involve power plant operators and maintenance
staff. The number of workers will depend on the size of the mill and the
number of boilers operated. Exposure levels to PCDDs and PCDFs associated
with this disposal technique, however, are not addressed in this report, but
rather are the subject of a report being developed by OAQPS.
2.3.2.3 Surface Impoundment--
Most of the pulp and paper mills that use surface impoundments pump
non-dewatered sludge or slurried bottom ash and fly ash directly to on-site
surface impoundments. There is no data available in the literature regarding
municipal or pulp and paper mill surface impoundment worker activities or job
categories. The only data available is from the 104-Mill Study, which stated
that the sludge is pumped to surface impoundments. Given this description,
it was assumed that there would probably be no workers dedicated only to a
pumping operation but rather these operations would be handled by the waste
treatment operators. Thus, the workers involved in surface impoundment
operations have already been counted in the waste treatment operator category
previously described.
2-25
-------
2.3.2.4 Land Application--
One job category of workers is postulated for land application opera-
tions: equipment operators who are dedicated to land application operations
only. Sludge application will involve equipment operators to operate
fertilizer spreaders, tank trucks, plows, bulldozers, or other equipment
depending on the type of sludge application. The number of equipment opera-
tors will depend on the quantity of sludge to be disposed, the sludge appli-
cation techniques, and whether one operator is exclusively dedicated to one
piece of equipment.
Typical activities of land application equipment operators will center
around their equipment. The land application equipment operator will drive
the equipment which spreads and plows the sludge into the ground. These
activities may include maintenance and cleanup of the equipment as well.
The land application equipment operator population exposed to PCDDs and
PCDFs is estimated to be approximately 20 workers. This estimate is based on
the assumption that there are 2 equipment operators on one shift within the 7
mills which dispose of sludge by land application. It was assumed that a
dedicated operator was necessary for spreading and plowing equipment, respec-
tively. This assumption represents worst-case conditions as the spreading
and plowing equipment may not each have a dedicated operator. Typically,
however, spreading and plowing equipment will have dedicated operators.
Also, it is assumed that the equipment operators are dedicated to land appli-
cation operations. Given that land application can be seasonal, the latter
assumption also represents worst-case conditions on exposed population esti-
mates.
2-26
-------
2.3.2.5 Distribution of Sludge as a Salable Product--
Sludge is converted into a salable product by heat-drying or composting.
Heat-drying will require skilled operators for the dryers (EPA 1979). Other
employees may be used to aid in conveying and bagging of the dried sludge
prior to shipment to fertilizer manufacturers. The fertilizer manufacturing
operations will employ various personnel in the processing of the dried
sludge.
Composting operations may involve personnel not affiliated with the pulp
and paper mill when composting is done off-site, as is generally the case.
These operations are usually conducted only during the daylight shift. There
may be three job categories of workers in composting operations: equipment
operators, screen operators, and compost haulers. Equipment operators
perform unloading and placement of the sludge into windrows or aerated piles.
In windrow composting, equipment operators operate turning machines which mix
the composting sludge. Equipment operators remove the compost from the
windrows and piles and load it into screens. They also load the finished
compost into dump trucks for distribution. A municipal sewage sludge com-
posting operation that uses windrow composting techniques to process 400 to
600 wet tons of sludge daily employs 20 operators and mechanics per shift
(excluding sludge haulers). Another municipal sewage sludge composting
operation that uses aerated pile composting techniques to process 60 to 120
wet tons of sludge daily employs 6 people per shift (excluding sludge
haulers). If the compost is screened, an equipment operator and screen
operator are necessary (EPA 1979). Other personnel may be required if the
compost is ground, blended or further processed in some manner prior to
2-27
-------
distribution. The screen operator is responsible for proper maintenance and
operation of the screen, e.g., unplugging the screen if the compost is too
wet. The compost hauler transports the finished product to farms or other
facilities which may further process the compost.
The equipment operator population exposed to PCDDs and PCDFs is estimated
to be approximately 150 workers, based on the assumption that there are 20
operators on one shift within the 7 mills that dispose of sludge through
composting. The number of equipment operators was derived from the EPA 1979
study which showed that a composting operation handling 80 to 120 dry tons of
sludge/day (the average sludge production for mills which practice distribution
of sludge as a salable product was 80.5 dry tons/day as shown in Table 2-1)
used 20 equipment operators.
The screen operator population exposed to PCDDs and PCDFs is estimated
to be approximately 20 workers, based on the assumption that there are 2
screen operators on one shift within the 7 mills that dispose of sludge
through composting. This assumption represents worst-case conditions, as
only one screen operator may be employed; however, the extent of this occur-
rence in the industry is unknown. The compost hauler population exposed to
PCDDs and PCDFs is estimated to be approximately 50 workers, based on the
assumption that there are 7 haulers on one shift within the 7 mills that
dispose of sludge through composting. The number of haulers was derived
based on average compost production and the assumption that 6 cubic yard dump
trucks were used and that each round trip took one hour. This assumptions
represents worst-case conditions as less haulers or larger dump trucks may be
employed; however, the extent of these occurrences in the industry is
unknown. Appendix E shows the calculations used to determine the number of
sludge haulers.
2-28
-------
The number of exposed workers in each job category for the various
sludge disposal operations are presented in the summary tables in Sections 3
and 5.
2-29
-------
SECTION 3
WORKER EXPOSURE
Although considerable data have been collected on concentrations of 2378
TCDD and 2378 TCDF for pulp, sludge, and wastewaters in the pulp and paper
industry, no inhalation or dermal exposure data for 2378 TCDD and 2378 TCDF
are currently available. This is in part because of the lack of a validated
sampling and analytical method for measuring worker exposure to these
chemicals. Furthermore, little information is available on the effectiveness
of engineering controls or the use of personal protective equipment in this
industry. PEI hence had to resort to exposure modeling techniques based on
numerous assumptions in order to estimate worker exposure to 2378 TCDD and
2378 TCDF.
Workers processing and commercially using pulp and paper sludge may be
exposed to 2378 TCDD and 2378 TCDF either through dermal contact with the
sludge or through inhalation exposure of either volatilized 2378 TCDD/2378
TCDF or particulates containing these chemicals. The potential for vola-
tilization exposure should be minimal because these chemicals have a low
vapor pressure and have a tendency to bind with organic matter rather than
volatilize freely. The inhalation exposure levels computed in this report
provide an estimate of the quantities of 2378 TCDD and 2378 TCDF that would
freely volatilize; the values hence represent worst-case estimates since the
effects on volatilization of 2378 TCDD and 2378 TCDF due to binding with
organic matter and from interferences due to other chemicals present in the
3-1
-------
sludge are not considered. There is some potential for inhalation exposure
from particulates during sludge handling operations such as loading/unloading
spreading, compacting, plowing into soil, and composting. There is some
potential for dermal exposure to 2378 TCDD and 2378 TCDF through handling of
contaminated sludge, although this would be minimal because most operations
are highly automated with generally little contact between the sludge and
employees except in cases of emergency maintenance and cleanup.
3.1 POTENTIAL FOR WORKER EXPOSURE
The potential for dermal and inhalation exposure from sludge processing,
disposal, and commercial use will vary in the industry depending on the job
description of the worker, extent of automation, and equipment layout.
3.1.1 Sludge Formation and Processing
In sludge formation and processing, the potential for PCDD and PCDF
exposure for waste treatment plant operators exists through dermal contact
with wet sludge when taking samples and when performing maintenance. Dermal
contact is otherwise limited by the high degree of automation of sludge
processing operations. Samples of dewatered sludge are usually taken once
per shift to determine if the dewatering equipment is operating properly.
Samples of non-dewatered sludge may also be taken (Fisher 1989). Contact.
with sludge can occur through cleanup of spills of non-dewatered sludge or
dewatered sludge that has fallen off the conveyors. Cleanup is usually done
with shovels, minimizing dermal contact (Hawks 1989). Repair of dewatering
equipment, pumps, and conveyors may also result in dermal contact. There
were no available data on the duration of dermal exposure to the waste treat-
ment plant operators. Since the process is highly automated and cleanup is
3-2
-------
usually done with a shovel, dermal exposure should be minimal. Therefore, as
a worst case, PEI estimates that typical maintenance and cleaning activities
may result in 2 hours of dermal contact with the wet sludge during a shift.
The potential for inhalation exposure to waste treatment operators
exists through volatilization of 2378 TCDD and 2378 TCDF in the wet sludge
and inhalation of particulate matter generated during sludge handling opera-
tions. Waste treatment plant operators may be exposed to 2389 TCDD and 2378
TCDF through volatilization when inspecting and/or repairing equipment,
taking samples, and cleanup of spilled sludge. There were no data available
on the duration of inhalation exposure to the waste treatment plant operators
from volatilization. The waste treatment plant operators are located near
the wastewater equipment for sampling, cleanup, and maintenance. These
activities were assumed to involve approximately half of the waste treatment
plant operator's 8-hour shift. Therefore, PEI estimated that the duration of
inhalation exposure via volatilization for a typical waste treatment plant
operator to be 4 hours per shift. Waste treatment plant operators may also
be exposed to 2378 TCDD and 2378 TCDF through the generation of particulate
matter during sludge handling operations. The quantity of particulate matter
generated is estimated to be minimal because of the high moisture content of
the sludge (approximately 70 percent). There were no available data on the
duration of inhalation exposure to the waste treatment plant operators from
particulate matter generated during sludge handling operations. Particulate
matter is generated during loading and unloading from the sludge storage
pile; these activities will typically be handled by haulers and front-end
loader operators. Since the waste treatment plant operator would only be in
the area during sampling and cleanup, the duration of inhalation exposure to
3-3
-------
particulate matter should be minimal for the waste treatment plant operator.
Therefore, PEI estimated that the typical waste treatment plant operator
would be exposed to 2378 TCDD and 2378 TCDF through inhalation of particulate
matter generated during sludge handling for approximately 1 hour per shift.
Sludge haulers and front-end loader operators may be exposed to PCDDs
and PCDFs through handling and loading of the sludge. Front-end loader
operators remove the sludge from a pile and load it into the dump truck. The
sludge haulers then transport the sludge to its final disposal site. Expo-
sure to 2378 TCDD and 2378 TCDF may occur through inhalation of particulate
matter generated during sludge handling and loading, volatilization of 2378
TCDD and 2378 TCDF from the wet sludge, and dermal contact during maintenance
activities. It is estimated that these workers may be exposed to 2378 TCDD
and 2378 TCDF through volatilization and inhalation of particulate matter for
4 hours per shift, assuming loading activities represent half of the work
done during an 8-hour shift. The hauler spends the other half of his shift
transporting the sludge to its disposal site. The time of dermal exposure
for these workers is estimated to be 1 hour per shift because the equipment
operators will generally not be in contact with the wet sludge unless
maintenance is required.
The following is an estimation of both inhalation and dermal exposures
for waste treatment operators, sludge haulers, and front-end loader opera-
tors. The concentrations of 2378 TCDD and 2378 TCDF in the sludge used for
the worker exposure calculations in sludge handling/processing operations are
the low and high concentrations for 2378 TCDD and 2378 TCDF reported for the
combined dewatered sludge from the 104-Mill Study corresponding to the
calculated low and high TEQ. These values were previously shov/n in Table
3-4
-------
2-5. Particulate matter emissions from sludge handling operations were
calculated using AP-42 emission factors and are documented in Appendix B;
exposed population calculations are also presented in Appendix B. Partic-
ulate matter emissions from sludge loading and unloading into dump trucks
were calculated using an emission factor for unloading and loading of various
materials presented in Section 11.2.3 of AP-42 (EPA 1988d). This approach
was taken after review of a EPA study (EPA 1988b), which presented a
methodology to calculate PCDD and PCDF releases using emission factors
presented in AP-42 (EPA 1988d).
3.1.1.1 Level of Inhalation Exposure--
In sludge handling/processing operations, there are three job categories
of workers (waste treatment plant operators, sludge haulers and front-end
loader operators) who are potentially exposed to 2378 TCDD and 2378 TCDF
through inhalation of vapors and particulate matter containing dioxin and
dibenzofuran. The inhalation exposure levels for sludge haulers and front-
end loader operators were treated the same because both are involved to a
similar degree in sludge-loading operations.
Volati1ization--There are no existing data available to determine
inhalation exposure from volatilization of 2378 TCDD/2378 TCDF during sludge
handling/processing. In the absence of exposure monitoring data, PEI
estimated worker exposure to 2378 TCDD/2378 TCDF using a mass balance model.
There are many mass balance models available for estimating worker
exposure. Table 3-1 presents some of the mass balance models (equations and
solutions) which can be used to estimate concentrations of a chemical ir an
enclosed space. Most of these models, however, are based on estimating
concentrations from point sources. During sludge handling/processing opera-
tions, volatilization occurs from an area source that is not in an enclosed
3-5
-------
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3-6
-------
area. At present, there are no widely accepted models for estimating on-site
concentrations from an area source. However, on-site 2378 TCDD/2378 TCDF
concentrations in air were estimated based on a "box model" approach, which
was used to simulate the dilution impacts of the wind in an out door setting,
by using Equation 3.
Cm = fi ) /v x 100° Equation 3
where:
Cm = 2378 TCDD/2378 TCDF vapor concentration in air, mg/m
G = generation rate of 2378 TCDD/2378 TCDF, g/sec
L = equivalent side length of the area source perpendicular to the
direction of the winds, m
MH = mixing height of vapors before inhalation by an individual, m
V = average wind speed at the inhalation height, m/sec
The average wind speed chosen was 2.2 m/s and the mixing height chosen
was 1.5 m (EPA 1988b). The length of the area-source in the direction of the
wind is calculated in Appendix B through E. The "box model" approach used
assumes that 2378 TCDD/2378 TCDF present at the site travels only a short
distance before it is inhaled by the worker.
The generation rate used in Equation 3 is calculated from Equation 4.
For Equation 4, there are many models which can be used to estimate an emis-
sion rate per unit area. Abt Associates explored two models for estimating
the emission rate per ur.it area from a landfill, herein referred to as the
"EPA Model" and the "SESOIL Model" (Abt 1989). The first model is based on
an emission rate per unit area from a set of Equations presented in EPA
(1986), and Hwang and Falco (1986) as described in EPA (1988b). The SESOIL
model uses Farmer's Equations to estimate the movement of volatilized con-
taminants between layers of the soil column, and estimates releases of the
contaminant from the topmost layer to the ambient air. The EPA model was
selected by PEI to estimate emission rates in this report since the EPA model
3-7
-------
is more conservative. Equations 5 through 7 present the equations for the
EPA model for calculating the emission rate per unit area.
G = Na x A
where:
2 x Dj x E4/3 x Kas x C
a (PI x ALPHA x T]1/2
and
Equation 4
Equation 5
ALPHA = Di x E
4/3
E + RHOs x (1 - E)/Kas
Kas = 41 Hc/Kd
Equation 6
Equation 7
Where:
G
Na
A
D
E
K
i
= generation rate in g/sec
= rate of emissions from the soil surface, g/cm2-s
= surface area where emissions occur, m2
= the molecular diffusivity of contaminant vapor in air, cmz/s
= effective porosity of soil, unitless
= the air/soil partition coefficient, mg/cm3 in air per mg/g in
soil
= the initial 2378 TCDD/2378 TCDF concentration in the soil, g/g
PI = mathematical constant, unitless (3.14159)
ALPHA = intermediate variable used to calculate rate of emissions from
the soil surface, cm2/s
T = duration of exposure, s
RHO = true density of soil, g/cm3
H = Henry's law constant, atm-m3/mole
K. = the soil/water partition coefficient,
as
so
in soil per -£- in water
Cfflg
The conversion factor of 41 in Equation 7 (based on the ideal gas law)
is needed to convert H /K. in the specified units to the units for Kgs. The
daily inhalation exposure from volatilization (in mg/day)is then calculated
using Equation 8. It should be noted that the calculated inhalation exposure
levels from volatilization are biased high because no percent reductions are
3-8
-------
incorporated in the calculations for 2378 TCDD/2378 TCDF binding with organic
matter and the presence of other chemicals in the matrices that could
interfere with the volatilization of the 2378 TCDD/2378 TCDF. No estimates
could be found in the literature or provided by knowledgeable contacts in the
field regarding the quantitative reductions in volatilization from such
interferences.
Iv = Cm x 1.25 m3/h x ED Equation 8
where: -
Cm = concentration of 2378 TCDD/2378 TCDF in the vapor, mg/m
Iv = daily inhalation exposure from volatilization, mg/day
ED = exposure duration, h/day
Table 3-2 summarizes the variables and results using Equations 3 through
8. It presents estimated daily inhalation exposure to 2378 TCDD and 2378
TCDF for waste treatment plant operators and haulers/front-end loader operators
via volatilization from wet sludge.
The relative toxicity of 2378 TCDF with respect to ?378 TCDD can be
determined by calculating toxicity equivalents (TEQ). In addition, the
percent exposure due to 2378 TCDD can also be calculated. Equation 9
presents the equation for calculating TEQ while Equation 10 is used for
calculating the percent of the exposure due to 2378 TCDD. These equations
are found in EPA 1989b. Table 3-3 presents the daily and lifetime average
daily TEQ and percent exposure due to 2378 TCDD from volatilization for
workers handling/ processing wet sludge.
DTEQv = !VTCDD +0.1 !VTCDF Equation 9
Trnn
%TCDDv = - 5^ x 100 Equation 10
where: TCDD TCDF
DTEQv = daily toxicity equivalents from volatilization of 2378 TCDD
and 2378 TCDF
IvTrnn = daily inhalation exposure to 2378 TCDD from volatilization,
IUJU mg/day
IvTrnF = daily inhalation exposure to 2378 TCDF from volatilization,
IUJh mg/day
%TCDDv = percent of the exposure from volatilization due to 2378 TCDD, %
3-9
-------
TABLE 3-2. ESTIMATED INHALATION EXPOSURE TO 2378 TCDD AND 2378 TCDF FOR
WASTE TREATMENT PLANT OPERATORS AND HAULERS/FRONT-END LOADER
OPERATORS FROM VOLATILIZATION
2378 TCDD
Variable
Low
High
2378 TCDF
Low
High
Reference
Henry's Law Con- 1.6xlO"5 1.6xlO"5 8.6xlO"5
stant, atm-mVmole
(He)
Soil/water parti- 1.4xl06 1.4xl06 4900
tion coefficient,
mg/g in soil per
mg/cm3 in water (Kd)
Air/soil partition 4.7xlO"10 4.7xlO"10 7.2xlO"7
coefficient,
mg/cm3 in air
per mg/g in soil
(Kas}
Molecular dif- 0.047 0.047 0.048
fusivity of
2378 TCDD/2378
TCDF in air,
cm2/s (Di)
Effective porosity
of soil , unitless
(E)
True density of
soil, g/cm3 (RHOg)
0.25
2.65
0.25
0.25
2.65
2.65
1.8x10
-12
"12
1.8x10 "- 2.7x10
"9
8.6x10
4900
-5
7.2x10
-7
Intermediate
variable to
calculate rate
of emission from
the soil surface,
cm2/s (ALPHA)
Initial 2378 TCDD/ 0.7xlO"12 1.39xlO"9 S.OxlO"12
2378 TCDF con-
centration in
the soil on a
dry basis, g/g
Duration of ex-
posure, s (T)
Emission rate of
2378 TCDD/2378
TCDF from the
soil surface,
g/cm2-s
(continued)
2.21xl09 2.21xl09 2.21xl09
_?? -?n -?i
4.4x10 " 8.8x10 ^ 7.5x10 ^
0.048
0.25
2.65
2.7x10
-9
1.71x10
-8
2.21X103
4.3xlO"17
Abt 1989
Abt 1989
Calculated
Abt 1989
Abt 1989
Abt 1989
Calculated
104-Mill
study data
Abt 1989
Calculated
3-10
-------
TABLE 3-2 (continued)
Variable
Surface area,
cm2 (A)
-haulers/front-
end loading
operators
-waste treat-
2378 TCDD
Low High
29,729 29,729
92,903 92,903
2378 TCDF
Low High Reference
29,729 29,729 See Table 3-5
92,903 92,903 See Table 3-5
322
ment plant
operators
Generation rate,
g/s (G)
-haulers/front- 1.3x10
end loading
operators
-waste treat-
ment plant
operators
Molecular weight,
g/g-mole (M)
Equivalent side
length of area
source perpen-
dicular to the
direction of the
wind, m(L)
-haulers/front-
end loading
operators
-waste treat-
ment plant
operators
Mixing height
of the vapors
before inhala-
tion by an
individual, m
(MH)
Average wind
speed of the
inhalation
height, m/s (V)
(continued)
2.6xlO"15 2.2xlO"16 1.3xlO"12
4.1xlO"18 S.lxlO"15 7.0xlO"16 4.0xlO"12
Calculated
Calculated
2.44
3.00
1.5
2.2
322
2.44
3.00
1.5
2.2
306
2.44
3.00
1.5
2.2
306 EPA 1989c
2.44
3.00
Appendix B
Appendix B
1.5 EPA 1988b
2.2 EPA 19885
3-11
-------
TABLE 3-2 (continued)
2378 TCDD
2378 TCDF
Variable
Low
High
Low
High
Reference
Concentration of
2378 TCDD/2378
TCDF in the
vapor, mg/m3(Cm)
-haulers/front- 1.6x10 1D 3.2x10 i>3 2.8x10 1.6x10 iu Calculated
end loader
operators ,g _,. .. .Q
-waste treat- 4.1x10 1D 8.2x10 1J 7.0x10 ^ 4.0x10 iu Calculated
ment plant
operators
Exposure dura-
tion, h/day (ED)
-haulers/front- 4 4 4
end loader
operators
-waste treat- 444
ment plant
operators
4 See Table 3-5
4 See Table 3-5
Daily inhalation,
rug/day (Iv) ., _,? ,. _,n
-haulers/front- 8.1x10 iD 1.6x10 ^ 1.4x10 ij 7.9x10 iu Calculated
end loader
operators ,, _,? 13 _g
-waste treat- 2.1x10 15 4.1x10 ^ 3.5x10 1J 2.0x10 y Calculated
ment plant
operators
3-12
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3-13
-------
In addition to daily TEQ, the lifetime average daily TEQ (LTEQv) for
workers was also calculated. This is presented in Equation 10:
LTEQv = DTEQv x DY x LF/(BW x LE) Equation 11
where:
LTEQv = lifetime average daily TEQ from volatilization, mg/day-kg
DTEQv = daily TEQ from volatilization, rug/day
DY = number of days per year exposed, day/year
LF = number of years of exposure per lifetime, years/lifetime
BW = average body weight for a worker, kg
LE = lifetime expectancy, days/lifetime
The number of years of exposure per lifetime (LF) was assumed to be 40
years and the lifetime expectancy (LE) was assumed to be 25,550 days (i.e.,
70 years). The average body weight for male workers (BW) is 70 kg and a
female worker is 58 kg (NCASI 1988). PEI assumed that the worker would be in
the plant for 250 days per year. Table 3-3 presents the lifetime average
daily TEQ. Table 3-4 presents the assumptions and uncertainties of those
variables used to calculate lifetime average daily TEQ from daily TEQ.
Table 3-5 presents the assumptions and uncertainties in the variables
used to calculate inhalation exposure from volatilization from wet sludge as
presented in Tables 3-2.
The following is an example of the calculation procedure used for esti-
mating levels of daily inhalation exposure to 2378 TCDD and 2378 TCDF from
volatilization from wet sludge:
Lower limit of 2378 TCDD inhalation exposure levels from volatilization for
haulers/front-end loader operators
Kas = 41 Hc/Kd
= 41 x 1.6xlO"5/1.4xl06
= 4.7x10" rug/cm3 in air per mg/g in soil
3-14
-------
TABLE 3-4. ASSUMPTIONS AND UNCERTAINTIES IN VARIABLES FOR
CALCULATING LIFETIME AVERAGE DAILY TEQ FROM DAILY TEQ
Uncertainty
Associated
assumption
Reasonable
possible variance
of assumption
Effects
on results
Number o.f days per
year workers are
exposed.
Number of years of
exposure per
lifetime
Average body weight
of a worker
The lifetime expect-
ancy of worker
Workers were assumed
to be exposed for
250 days per year.
(PEI estimate)
Workers were assumed
to be exposed for 40
years. (EPA 1989b)
The average body
weight of a male
worker is 70 kg and
a female worker is
58 kg (NCASI 1988).
Workers were assumed
to live for 70 years
(NCASI 1988).
A maximum exposure
duration is 365
days.
Maximum of
1.5 times
greater
exposure.
3-15
-------
TABLE 3-5. ASSUMPTIONS AND UNCERTAINTIES IN ESTIMATING INHALATION EXPOSURE TO
2378 TCDD AND 2378 TCDF FOR WASTE TREATMENT PLANT OPERATORS AND
HAULERS/FRONT-END LOADER OPERATORS FROM VOLATILIZATION
Uncertainty
Associated
assumption
Reasonable
possible variance
of assumption
Effects on results
The open surface area
where the hauler/front
end loader operator
would be exposed to
2378 TCDD and 2378 TCDF.
The open surface area
where the waste treatment
plant operator would be
exposed to 2378 TCDD
and 2378 TCDF.
Inhalation exposure
duration for hauler/
front end loader
operator.
Inhalation exposure
duration for waste
treatment plant
operator.
The open surface
area of a dump
truck was assumed
to be 4 ft by 8
ft on a 6 yd3
dump truck.
The open surface
area of a
conveyor was
assumed to be
2.5 ft by 40 ft.
The duration of Reasonable range Exposure would
the exposure was
assumed to be 4
hours since the
operator conducts
loading opera-
tions for 1/2
the shift.
The duration of
the exposure was
assumed to be 4
hours since the
operator is near
the equipment for
1/2 the shift.
in the duration
would be 2 to 8
hours.
range from 0.5 to
2 times the
exposure level.
Reasonable range
in the duration
would be 2 to 8
hours.
Exposure would
range from 0.5 to
2 times the
exposure level.
3-16
-------
D, XE4/3
ALPHA = 1
E + RHOs x (1-E) K
u S
= 0.047 x (0.25)4/3
0.25 + 2.65 (l-0.25)/4.7xl010
= 1.8 x 10"12 cm2/s
Na = 2 x DI x E4/3 x Ka$ x C$0
[PI x ALPHA x T]1/2
= 2 x 0.047 x (0.25)4/3 x 4.7 x 10"10 x 0.7 x 10"12
12 9 1/2
[3.14159 x 1.8 x lO"1^ x 2.21 x 10y]
= 4.4 x 10"23 g/cm2-s
G = Na x A
v"£J
cm -s
= 4.4 x 10"23 -2 x 29,729 cm2
= 1.3 x 10"18 g/s
Cm = (L) (MH) (V) x 100°
,-18
1.3 x 10" g/s innn
(2.44m) (1.5m) (2.2 m/s) X 10°°
= 1.6 x 10"16 mg/m3
Iv = 1.6 x 10"16 mg/m3 x 1.25 m3/h x 4 h/day
= 8.1 x 10"16 mg/day
The following Is an example of the calculation procedure for estimating
TEQ and percent daily exposure due to 2378 TCDD from volatilization from wet
sludge.
3-17
-------
Lower limit for daily TEQ and percent daily exposure due to 2378 TCDD for
haulers/ front-end loader operators from volatilization
TEQv = 8.1 x 10~16 + (0.1 x 1.4 x 10"13)
= 1.5 x 10"14 mg/day
8.1 x 10"16
%TCDDv = 8.1 x 1CT16+ 1.4 x 10-13 xl°°
= 0.6%
The following is an example of the calculation procedure for estimating
lifetime average daily TEQ.
Lower limit for lifetime average daily TEQ from volatilization
LADEv = (1.5 x 10 mg/day x 250 days/yr x 40 years/lifetime)/
(70 kg x 25,550 days/lifetime)
= 8.2 x 10"17 mg/day-kg
Inhalation exposure from particulate matterEquation 12 was used to
calculate the inhalation exposure from 2378 TCDD and 2378 TCDF contained in
particulate matter generated during sludge handling/processing operations.
This equation is similar to equation 8 except that Cm in this equation repre-
sents the total particulate concentration rather than the 2378 TCDD and 2378
TCDF concentration.
Ip = Cm (mg/m3) x 1.25 m3/h x ED (h/day) x WF Equation 12
where Ip = daily inhalation from particulate matter, mg/day
Cm = concentration of particulate matter, mg/m3
WF = weight fraction of 2378 TCDD/2378 TCDF in the dry sludge
ED = exposure duration, h/day
The concentration of 2378 TCDD/2378 TCDF in the particulate matter was
assumed to be equal to the concentration of 2378 TCDD/2378 TCDF in the
sludge. The dry weight concentration of 2378 TCDD/2378 TCDF, as reported in
the 104-Mill Study, was used in the calculations because the particulate
matter which is emitted is assumed to be dry.
3-18
-------
The concentration of participate matter was calculated using Equation 13
(EPA 1988b).
Cm = (L)(MH)(V) Equation 13
where Cm = particulate concentration, mg/m
Qp = total particulate matter emission rate, mg/s
L = equivalent side length of the site perpendicular to the
direction of the winds, m
MH = mixing height of the particulate matter before inhalation by
an individual (assumed to be 1.5 m)
V = average wind speed at the inhalation height (assumed to be 2.2
m/s)
Equation 13 estimates the on-site concentration of particulate matter in
ambient air. It assumes that the particulate matter present at the site has
traveled only a short distance before it is inhaled by the workers. The
equation considers mixing of the particulate matter with winds but ignores
dispersion effects. Total particulate emission rates for a given disposal
scenario, which in this case is dewatered sludge loading and unloading, are
used in the equation. The length of the area from which the particulate
matter is being emitted corresponds to the length of an open area of the dump
truck, length of daily landfill and land application areas, and length of the
area of composting activities. The mixing height corresponds to the height
at which the individual would inhale the particulate matter and the wind
speed corresponds to the wind speed at the inhalation height.
The assumed values for mixing height and wind speed used in the release
calculations from Equation 13 are suggested average default values presented
in the EPA 1988b study. Particulate matter emission rate for sludge handling
were calculated using AP-42 emission factors and concentration calculations
are presented in Appendix B. These AP-42 emission factors are widely used
for estimating particulate emission rates for similar applications.
3-19
-------
Table 3-6 summarizes the variables used to calculate the exposure to
workers from the particulate matter containing PCDDs and PCDFs generated
during sludge handling/processing operations. It presents estimated daily
inhalation exposure to 2378 TCDD and 2378 TCDF for waste treatment plant
operators and haulers/front-end loader operators from particulate matter.
The relative toxicity of 2378 TCDF in respect to 2378 TCDD can be
determined by calculating TEQ values. The percent exposure due to 2378 TCDD
can also be calculated. Equations 9 and 10 are used to calculate these two
variables. In these two equations, the daily inhalation exposure from
volatilization (Iv) for 2378 TCDD and 2378 TCDF are replaced with the daily
inhalation exposure from particulate matter (Ip) for 2378 TCDD and 2378 TCDF.
Table 3-7 presents the daily and lifetime average daily TEQ and percent
exposure due to 2378 TCDD from particulate matter for workers handling/
processing sludge.
The following is an example of the calculation procedure used for esti-
mating levels of daily inhalation exposure for haulers/front-end loader
operators exposed to 2378 TCDD from particulate matter:
Lower limit for 2378 TCDD inhalation exposure level from particulate matter
for haulers/front-end loader operators
Ip = 0.017 mg/m3 x 1.25 m3/h x 4 h/day x 0.7 x 10"12
= 5.9 x 10"14 mg/day
The following is an example of the calculation procedure for estimating
TEQ and percent daily exposure due to 2378 TCDD from particulate matter.
Lower limit for daily TEQ and percent daily exposure due to 2378 TCDD for
haulers/front-end loader operators from particulate matter
TEQp = 5.9 x 10"14 + (0.1 x 2.6 x 10"13)
= 8.5 x 10"14 mg/day
3-20
-------
TABLE 3-6. ESTIMATED INHALATION EXPOSURE TO 2378 TCDD AND 2378 TCDF
FOR WASTE TREATMENT PLANT OPERATORS AND HAULERS/FRONT-END LOADER
OPERATORS FROM PARTICULATE MATTER
Variable
2378 TCDD
Low
High
2378 TCDF
Low
High
Reference
Concentration of
particulate matr
ter, mg/m3 (Cm)
- haulers/front- 0.017
end loader
operators
- waste treat-
ment plant
operators
Weight fraction
of 2378 TCDD/
2378 TCDF in
the dry sludge,
dry basis (WF)
Exposure dura-
tion, h/day (ED)
- haulers/front- 4
end loader
operators
- waste treat- 1
ment plant
operators
Daily inhalation,
mg/day (Ip)
- haulers/ 5.9x10
front-end
loader
operators
- waste treat- 8.3x10
ment plant
operators
0.017 0.017
0.0095 0.0095 0.0095
0.7xlO"12 1.39xlO"9 3.0xlO"12
0.017 Calculated (see
Appendix B)
0.0095 Calculated (see
Appendix B)
1.71xlO"8 (Table 2-5, 104-
Mill Study data)
4
1
4
1
-14
-15
.2xlO"10 2,
1.7xlO"U 3,
6x10
-13
6x10
-14
4 Engineering
judgment
1 Engineering
judgment
1.5xlO"9 Calculated
2.0xlO"10 Calculated
These concentrations are below the OSHA nuisance dust standard of 15 mg/m3.
The haulers would be exposed to particulate matter during loading and
unloading the sludge. Since the haulers spend approximately half the shift
loading and unloading sludge, it was estimated the workers would be exposed
to particulate matter for 4 hours per day.
The waste treatment plant operator would only be in the area during sampling
and cleanup, there would be minimal exposure potential to particulate matter.
Therefore, it was estimated the exposure duration would be 1 hr/day.
3-21
-------
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3-22
-------
C Q Y in
%TCDDp = i/ 1U r* x 100
5.9 x 10"i4 + 2.6 x 10"1J
= 19%
3.1.1.2 Level of Dermal Exposure--
Dermal exposure levels to 2378 TCDD and 2378 TCDF were computed based on
the assumption that workers do not wear any types of gloves that are effective
in limiting exposure to PCDDs and PCDFs. Dermal exposure levels for sludge
haulers and front-end loader operators were assumed to be equal because of
their similar job functions.
There are a few different approaches available for estimating dermal
exposure. The approach selected by PEI was that agreed upon by EPA, Federal
Drug Administration, and the Consumer Product Safety Commission (EPA 1989d)
for use in this project. This approach considers the partitioning of
PCDD/PCDF fron the appropriate matrix (e.g., soil, sludges, pulp, paper) to a
liquid (i.e., water, skin oils, urine, blood) and percutaneous absorption of
PCDDs and PCDFs from the liquid. In this reference, common assumptions for
the assessment of dermal exposure are presented. However, in this reference,
equations for estimating dermal exposures were not present. CPSC supplied
three equations to PEI for estimating dermal exposure (CPSC 1989). These
equations are for estimating dermal exposure to pulp, paper, and sludge/soil.
The equation for handling wet sludge/soil was selected for the sludge haulers
and front-end loader operator handling wet sludge and is presented in
Equation 14.
DEW = DC (ppt) x p (mg/cm3) x FT (cm) x B x AD (h"1) x S (cm2)
x ED (hr/day) Equation 14
3-23
-------
where:
DEW = dermal exposure from handling wet material, mg/day
DC = adjusted 2378 TCDD/2378 TCDF concentration to account for
handling of wet sludge, ppt -
p = density of the dewatered sludge, mg/cm
FT = liquid film thickness, cm
B = bioavailability factor for sludge, unitless ,
AD = absorption coefficient of TCDD/TCDF through the skin, h
S = skin surface area, cm
ED = exposure duration, h/day
The 2378 TCDD and 2378 TCDF concentrations for sludge from Table 2-5 are
reported on a dry basis. Since the workers are handling wet sludge, this
concentration was adjusted to a wet basis by adjusting for the estimated
percent solids (30%) in the sludge. This corresponds to reducing the dry
2378 TCDD/2378 TCDF concentrations reported in the 104-Mill Study by a factor
of 3.33.
No data were available on duration or extent of dermal exposure. There-
fore, dermal exposure duration was based on engineering judgment. It was
assumed that only the palms and fingers of both hands of the hauler/front-end
loader operator would be in contact with the wet sludge, whereas it was
assumed that both hands and forearms of the waste treatment plant operator
would be in contact with the wet sludge. The density for dewatered sludge is
o
1058 mg/cm (EPA 1979) and a liquid film thickness for the wet sludge was
estimated to be 0.025 cm. It was estimated that 2378 TCDD was absorbed at an
average rate of approximately 0.012 h~ (AD) over the time period from 0.5 to
17 hours (EPA 1989d). For the purposes of risk assessment, it was assumed
that 15 percent of the sludge-bound 2378 TCDD is available for absorption
3-24
-------
(B) (EPA 1989d). Table 3-8 summarizes the variables and results for dermal
exposure of waste treatment plant operators and haulers/front-end loader
operators to wet sludge.
The relative toxicity of 2378 TCDF in respect to 2378 TCDD can be
determined by calculating TEQ values. The percent exposure due to 2378 TCDD
can also be calculated. Equations 9 and 10 are used to calculate these two
variables. In these two equations, the daily inhalation exposure from
volatilization (Iv) for 2378 TCDD and 2378 TCDF are replaced with the daily
dermal exposure (DEW) for 2378 TCDD and 2378 TCDF. Table 3-9 presents the
daily and lifetime average daily TEQ and percent exposure due to 2378 TCDD
from dermal exposure for workers handling/processing sludge. Table 3-10
presents the assumptions and uncertainties in the variables used to calculate
the dermal exposures for workers handling/processing wet sludge in Table 3-8.
The following is an example of the calculation procedures used for
estimating levels of daily dermal exposure for haulers/front-end loader
operators potentially exposed to 2378 TCDD and 2378 TCDF during the handling
of wet sludge:
Lower limit for 2378 TCDD dermal exposure level for haulers/front-end loader
operators
DEW = 0.21 x 10"12 2 x 1058 mg/cm3 x 0.025 cm x 0.15 x 0.012 h'1 x
250 cm2 x 1 hr/day
= 2.5 x 10"12 mg/day
3-25
-------
TABLE 3-8. ESTIMATED DERMAL EXPOSURE TO 2378 TCDD AND 2378 TCDF FOR
WASTE TREATMENT PLANT OPERATORS AND HAULERS/FRONT-END LOADER OPERATORS
2378 TCDD
2378 TCDF
Variable
Low
High
Low
High
Reference
2378 TCDD/2378 TCDF
concentration,
of wet sludge,
wet basis ppt (DC)
Density of the
sludge, mg/cm3
(P)
Liquid film thick-
ness of the
sludge, cm (FT)
Bioavailability
factor for sludge,
unitless (B)
Absorption coef-
ficient of
TCDD/TCDF through
the skin, h"1
(AD)
Skin surface
area, cm2 (S)
- haulers/
front-end
loader
operators
- waste treat-
ment plant
operators
Exposure dura-
tion, h/day (ED)
- haulers/front-
end loader
operators
- waste treat-
ment plant
opertors
(continued)
0.21
1058
0.025
0.15
0.012
250
2600
2
417 0.90 5,135 See Table 3-10
1058 1058 1058 EPA 1979
0.025 0.025 0.025 See Table 3-10
0.15
300
0.15
0.012 0.012
250
2600 2600
1 1
2 2
0.15 EPA 1989d
0.012 EPA 1989d
300 See Table 3-10
2600 See Table 3-10
1 See Table 3-10
2 See Table 3-10
3-26
-------
TABLE 3-8 (continued)
2378 TCDD 2378 TCDF
Variable Low High Low High Reference
Dermal exposure,
ing/day (DEW) ,? q n R
- haulers/ 2.5x10 6.0x10" 1.1x10" 7.3x10" Calculated
front-end
loader
operators ,, 7 ,n fi
- waste treat- 5.2X10"11 1.0x10"' 2.2xlO"IU 1.3x10"° Calculated
ment plant
operators
3-27
-------
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3-30
-------
3.1.2 Sludge Disposal Operations
The route and amount of exposure to 2378 TCDD and 2378 TCDF in sludge
disposal operations will depend on the specific sludge disposal technique,
the amount of sludge disposed, and the degree of processing of the sludge.
In addition, atmospheric events such as wind and rain will affect the degree
of exposure in sludge disposal operations conducted outdoors.
3.1.2.1 Landfilling Operations--
Inhalation is the primary route of exposure to 2378 TCDD and 2378 TCDF
in landfilling operations. During unloading, spreading, compacting, and
burying of the sludge with various pieces of equipment, particulate matter is
generated which may be inhaled by the equipment operators. In addition, 2378
TCDD and 2378 TCDF may volatilize from the wet sludge and be inhaled. It is
estimated that the equipment operators may be exposed to 2378 TCDD and 2378
TCDF by inhalation throughout their 8-hour shift because their only job
function is to operate equipment which is constantly in contact with the
sludge, and operations are conducted in open areas.
Dermal exposure to the wet sludge is minimal. It is estimated that the
time of dermal exposure for the equipment operators is 1 hour per shift
because they are generally not in contact with the wet sludge unless mainten-
ance of the equipment is required.
The following is an estimation of both dermal and inhalation exposures
for equipment operators at landfilling operations. The concentrations of
2378 TCDD and 2378 TCDF in sludge used in the exposure calculations for
landfill equipment operators are the low and high concentrations in sludges
which are landfilled as reported in the 104-Mill Study data corresponding to
the calculated low and high TEQ. The mills which practice landfill disposal
3-31
-------
of sludge were identified in the 104-Mill Study data provided by EPA. Partic-
ulate matter emissions from landfill ing sludge were calculated using AP-42
emission factors and are documented in Appendix C; exposed population calcula-
tions are also presented in Appendix C.
Particulate matter emissions from unloading, spreading, and composting
the sludge during landfill ing operations were calculated using emission
factors from AP-42 (EPA 1985 and EPA 1988d). The emission factors for unload-
ing various materials is presented in Section 11.2.3 of AP-42 (EPA 1988d).
The emission factor for agricultural tilling, presented in Section 11.2.2 of
AP-42 (EPA 1985), was used to estimate emissions from composting and spread-
ing. The agricultural tilling emission factor was used to estimate particu-
late emissions from spreading because this was the suggested emission factor
in a EPA study (EPA 1988b). All of these emission factors were used because
the methodology to calculate PCDD/PCDF releases from particulate matter
presented in EPA 1988b uses particulate matter emission factors taken from
AP-42 (EPA 1985 and EPA 1988d).
Level of inhalation exposureIn landfill ing operations one job category
of workers (i.e., equipment operators) is potentially exposed to 2378 TCDD
and 2378 TCDF through inhalation of vapors and particulate matter containing
dioxin and dibenzofuran. All equipment operators were assumed to be exposed
for the entire 8 hours of their shift, since their only job function is to
operate equipment which has continual contact with the sludge.
The same calculation procedures previously employed to estimate inhala-
tion exposure to 2378 TCDD and 2378 TCDF by volatilization (using Equations 3
through 8) and particulate matter generation (using Equation 12) for waste
treatment plant operators and sludge haulers/front-end loader operators were
3-32
-------
used to estimate inhalation exposures for landfill equipment operators.
Appendix C presents the calculations of particulate emission rates (based on
AP-42 emission factors), equivalent length of the area source, and concen-
trations used in the particulate exposure estimations. Table 3-11 summarizes
the variables used to calculate inhalation exposure levels for the landfill
equipment operators from volatilization from wet sludge and presents sub-
sequent exposure estimates.
The relative toxicity of 2378 TCDF in respect to 2378 TCDD can be deter-
mined by calculating TEQ values. In addition, the percent exposure due to
2378 TCDD can also be calculated. Using equations 9 and 10, these two vari-
ables are calculated. Table 3-12 presents the daily and lifetime average
daily TEQ and percent exposure due to 2378 TCDD from volatilization from wet
sludge for landfill equipment operators. Table 3-13 presents the assumptions
and uncertainties in the variables used to calculate the daily exposure for
the landfill equipment operators from volatilization.
Table 3-14 summarizes the variables for inhalation of particulate matter
generated from sludge unloading, spreading, compacting, and covering opera-
tions at landfills. It presents estimated daily inhalation exposure to 2378
TCDD and 2378 TCDF to landfill equipment operators from particulate matter.
The relative toxicity of 2378 TCDF in respect to 2378 TCDD can be deter-
mined by calculating TEQ values. The percent exposure due to 2378 TCDD can
also be calculated. Equations 9 and 10 are used to calculate these two
variables. In these two equations, the daily inhalation exposure from vola-
tilization (Iv) for 2378 TCDD and 2378 TCDF are replaced with the daily
exposure from particulate matter (Ip) for 2378 TCDD and 2378 TCDF. Table
3-15 presents the daily and lifetime average daily TEQ and percent exposure
due to 2378 TCDD from particulate matter for landfill equipment operators.
3-33
-------
TABLE 3-11. ESTIMATED INHALATION EXPOSURE TO 2378 TCDD AND 2378 TCDF
FOR LANDFILL EQUIPMENT OPERATORS FROM VOLATILIZATION
2378 TCDD
2378 TCDF
Variable
Low
High
Low
High
Reference
Henry's Law Con- 1.6xlO"5 1.6x10 8.6x10
stant, atm-m3/mole
(He)
Soil/water parti- 1.4xl06 1.4xl06 4900
tion coefficient,
mg/g in soil per
mg/cm3 in water (Kd)
Air/soil partition 4.7xlO"10 4.7xlO"10 7.2xlO"7
coefficient,
mg/cm3 in air
per mg/g in soil
8.6x10
4900
-5
7.2x10
-7
Abt 1989
Abt 1989
Calculated
Molecular dif- 0.047 0.047 0.048
fusivity of
2378 TCDD/2378
TCDF in air,
cm2/s (D1)
Effective porosity 0.25 0.25 0.25
of soil, unitless
(E)
True density of 2.65 2.65 2.65
soil, g/cm3 (RHO$)
1.8xlO"12 l.SxlO"12 2.7xlO"!
0.048
Abt 1989
0.25
2.65
2.7x10
-9
Intermediate
variable to
calculate rate
of emission from
the soiI surface,
cm2/s (ALPHA)
Initial 2378 TCDD/ 0.7xlO"12 7.1xlO"10 3.0xlO"12 1.09xlO"8
2378 TCDF con-
centration in
the soil on a
dry basis, g/g
Duration of ex-
posure, s (T)
Emission rate of
2378 TCDD/2378
TCDF from the
soil surface,
g/cm2-s
(continued)
2.21xl09 2.21xl09 2.21xl09 2.21xl09
4.4xlO"23 4.5xlO"20 7.5xlO"21 2.7xlO"17
Abt 1989
Abt 1989
Calculated
104-Mill
study data
Abt 1989
Calculated
3-34
-------
TABLE 3-11 (continued)
Variable
2378 TCDD
Low
High
2378 TCDF
Low
High
Reference
Surface area, 2.0x10
cm2 (A)
Generation rate, 8.8x10
9/s(6)
Molecular weight, 322
g/g-mole (M)
Mixing factor, 0.5
Equivalent side 14.2
length of the
area source
perpendicular
to the direction
of the wind,
m (L)
Mixing height 1.5
of the vapors
before inhala-
tion by an
individual, m
(MH)
Average windspeed 2.2
at the inhalation
height, m (V)
Concentration of 1.9x10
2378 TCDD/2378
TCDF in the
vapor, mg/m3 (Cm)
Exposure duration, 8
h/day (ED)
Daily inhalation 1.9x10"
mg/day (Iv)
6
2.0xl0
-17
9.0x10
322
0.5
14.2
-14
1.5
2.2
-15
1.9x10
-12
1.9x10
2.0xl06 2.0xl06 See Table 3-13
1.5xlO"14 5.4xlO"U Calculated
306
0.5
14.2
306 EPA 1989c
0.5 See Table 3-5
14.2 Appendix C
1.5
1.5 EPA 1988b
2.2
2.2 EPA 1988b
3.2xlO"13 1.2xlO"9 Calculated
8 8 See Table 3-13
3.2xlO"12 1.2xlO"8 Calculated
3-35
-------
TABLE 3-12. ESTIMATED TOXICITY EQUIVALENTS AND PERCENT EXPOSURE
DUE TO 2378 TCDD FOR LANDFILL EQUIPMENT OPERATORS FROM VOLATILIZATION
Daily TEQ, .
mg/day (DTEQv)a
Lifetime average
daily TEQ,
mg/day-kg (LTEQv)a
Low
High
Low
High
3.4xlO"13 (0.6%)
1.2xlO"9 (0.2%)
1.9xlO"15 (0.6%)
8.0xlO"12 (0.2%}
Values in parentheses are percent exposure due to 2378 TCDD.
TABLE 3-13. ASSUMPTIONS AND UNCERTAINTIES IN ESTIMATING INHALATION
EXPOSURE TO 2378 TCDD AND 2378 TCDF FOR LANDFILL EQUIPMENT OPERATORS
FROM VOLATILIZATION
Uncertainty
Associated
assumption
Reasonable
possible variance
of assumption
Effects on results
The open surface area
of an open landfill
where the workers
would be exposed to
2378 TCDD and 2378 TCDF
Inhalation exposure dur-
ation for landfill equip-
ment operators.
The daily appli-
cation surface
area was based on
applying 250 tons/
day (104 Mill
Study), specific
gravity of 1.06
(Hammer 1975) and
a rate of 5,700
ydVacre (EPA
1979). See
Appendix C for
calculations.
The duration of
the exposure was
assumed to be 8
hours since this
would be the worst
case exposure dur-
ation.
Reasonable range Exposure would
for the sludge range from 0.09 to
application rates 2.6 times greater
is 500 ft3/acre exposure.
to 15,000 ft3/
acre. This cor-
responds to 1.8x
105 cm2and 5.3xl06
cm2, respectively.
3-36
-------
TABLE 3-14. ESTIMATED INHALATION EXPOSURE TO 2378 TCDD AND 2378 TCDF FOR
LANDFILL EQUIPMENT OPERATORS FROM PARTICULATE MATTER
2378 TCDD 2378 TCDF
Variable Low High Low High Reference
Concentration of 0.62 0.62 0.62 0.62 Calculated
participate mat- (see Appen-
ter, mg/m3 (Cm) dix C)
Weight fraction of 0.7xlO"12 7.1xlO"10 S.OxlO"12 1.09xlO"8 104-Mill
2378 TCDD/2378 Study data
TCDF in the dry
sludge, dry
basis (WF)
Exposure dura- 8 8
tion, h/day
(ED)
Daily inhala- 4.3xlO"12 4.4xlO"9
tion, mg/day
(Ip)
8 8 Engineering
judgment
1.9xlO"U 6.8xlO"8 Calculated
a These concentrations are below the OSHA nuisance dust standard of 15 mg/m3,
The exposure duration was assumed to be 8 hours since this would be the
worst-case exposure duration.
TABLE 3-15. ESTIMATED TOXICITY EQUIVALENTS AND PERCENT EXPOSURE
DUE TO 2378 TCDD FOR LANDFILL EQUIPMENT OPERATORS FROM PARTICULATE MATTER
Lifetime average
Daily TEQ, daily TEQ,
mg/day (DTEQp)3 mg/day-kg (LTEQp)2
Low High Low High
6.2xlO"12 (19%) l.lxlO"8 (6%) 3.5xlO"14 (19%) 7.5xlO"U (6%)
3 Values in parentheses are percent exposure due to 2378 TCDD.
3-37
-------
Level of dermal exposureDermal exposure levels were based on the
assumption that the equipment operators do not wear any types of gloves that
are effective in limiting exposure to PCDDs and PCDFs. The same calculation
procedure as that used to estimate dermal exposure for waste treatment plant
operators and haulers/front-end loader operators was used to estimate dermal
exposure levels for the landfill equipment operator.
The.2378 TCDD and 2378 TCDF concentrations for sludge from Table 2-5 are
reported on a dry basis. Since the workers are handling wet sludge, this
concentration was adjusted to a wet basis by adjusting for the estimated
percent solids (30%) in the sludge. This corresponds to reducing the 2378
TCDD/2378 TCDF concentrations by a factor of 3.33.
In the absence of data on the extent and duration of dermal exposure,
dermal exposure duration was based on engineering judgment. It was assumed
that only the palms and fingers of both hands of the landfill equipment
operator would come in contact with the wet sludge. The density for de-
3
watered sludge is 1058.8 mg/cm and a liquid film thickness for the wet
sludge was estimated to be 0.25 mm. Table 3-16 summarizes the variables and
results for dermal exposure for landfill equipment operators.
The relative toxicity of 2378 TCDF in respect to 2378 TCDD can be deter-
mined by calculating TEQ values. The percent exposure due to 2378 TCDD can
also be calculated. Equations 9 and 10 are used to calculate these two
variables. In these two equations, the daily inhalation exposure from vola-
tilization (Iv) for 2378 TCDD and 2378 TCDF are replaced with the daily
dermal exposure (DEW) for 2378 TCDD and 2378 TCDF. Table 3-17 presents the
daily and lifetime average daily TEQ and percent exposure due to 2378 TCDD
from dermal exposure for landfill equipment operators. Table 3-18 presents
3-38
-------
TABLE 3-16. ESTIMATED DERMAL EXPOSURE TO 2378 TCDD AND 2378 TCDF
FOR LANDFILL EQUIPMENT OPERATORS
2378 TCDD
Variable
Low
High
2378 TCDF
Low
High
Reference
2378 TCDD/2378 TCDF 0.21
concentration of wet
sludge, wet basis,
ppt (DC)
213
0.90
3273 See Table 3-18
Density of the
sludge, mg/cm3
(P)
1058
Liquid film thick- 0.025
ness of the sludge,
cm (FT)
Bioavailability 0.15
factor for sludge,
unitless (B)
Absorption coef- 0.012
ficient of
TCDD/TCDF through
the skin, h"1
(AD)
Skin surface 250
area, cm2 (S)
Exposure dura- 1
tion, h/day
(ED)
Dermal expo- 2.5x10
sure, mg/day
(DEW)
-12
1058
0.025
0.15
0.012
300
3.1x10
-9
1058
0.025
0.15
0.012
250
1058 EPA 1979
0.025 See Table 3-10
0.15 EPA 1989d
0.012 EPA 1989d
300 See Table 3-18
1 See Table 3-18
l.lxlO"11 4.7xlO"8 Calculated
3-39
-------
TABLE 3-17. ESTIMATED TOXICITY EQUIVALENTS AND PERCENT EXPOSURE
DUE TO 2378 TCDD FOR LANDFILL EQUIPMENT OPERATORS FROM DERMAL EXPOSURE
Lifetime average
Daily TEQ, daily TEQ,
mg/day (DTEQd)3 mg/day-kg (LTEQd)a
Low High Low High
3.6xlO"12 (19%) 7.7xlO"9 (6%) 2.0xlO"14 (19%) 5.2xlO"U (6%)
a Values in parentheses are percent exposure due to 2378 TCDD.
3-40
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3-41
-------
the assumptions and uncertainties in the variables used to calculate the
dermal exposures for landfill equipment operators in Table 3-16.
3.1.2.2 Land Application
Exposure to 2378 TCDD and 2378 TCDF through land application is very
similar to that of landfilling operations. Inhalation is the primary route
of exposure to 2378 TCDD and 2378 TCDF in land application operations.
Particulate matter generated during unloading, spreading, and plowing opera-
tions may.be inhaled by the equipment operators. In addition, 2378 TCDD and
2378 TCDF may volatilize from the wet sludge and consequently be inhaled. It
is estimated that the equipment operators may be exposed via inhalation
throughout their entire 8-hour shift because their only job function is to
operate equipment which has continuous contact with the sludge, and operations
are performed in open areas.
It is assumed that land application operations are conducted throughout
the year. Operations could be seasonal, but in as much as some facilities
apply their sludge to pine tree plantations, PEI assumed, for worst-case
conditions, that land application operations are performed daily.
Dermal exposure to the wet sludge is minimal. It is estimated that the
time of dermal exposure for the equipment operators is only 1 hour per shift
because they are generally not in contact with the wet sludge unless main-
tenance of the equipment is required.
The following is an estimation of both inhalation and dermal exposure
for equipment operators at land application operations. The concentrations
of 2378 TCDD and 2378 TCDF in sludge used for the exposure calculations for
land application equipment operators are the low and high concentrations
reported for the sludges disposed by land application as reported in the
104-Mill Study data corresponding to the calculated low and high TEQ. The
mills which practice disposal of sludge by land application were identified
3-42 ,
-------
in the 104-Mill Study data provided by EPA. Participate matter emissions
from land application of sludge were calculated using AP-42 emission factor
and are documented in Appendix D; exposed population calculations are also
presented in Appendix D.
Particulate matter emissions from unloading, spreading, and plowing the
sludge during land application operations were calculated using emission
factors from AP-42 (EPA 1985 and EPA 1988d). The emission factor for
unloading various materials is presented in Section 11.2.3 of AP-42 (EPA
1988d). The emission factor for agricultural tilling, presented in Section
11.2.2 of AP-42 (EPA 1985), was used to estimate emissions from compacting
and spreading. The agricultural tilling emission factor was used to estimate
particulate emissions from spreading because this was the suggested emission
factor in EPA 1988b. All of these emission factors were used because the
methodology to calculate PCDD/PCDF releases from particulate matter presented
in the EPA 1988b study uses particulate matter emission factors taken from
AP-42 (EPA 1985 and EPA 1988d).
Level of inhalation exposureIn land application operations, there is
one job category of workers (i.e., equipment operators) potentially exposed
to PCDDs and PCDFs through inhalation of vapors and particulate matter contain-
ing dioxin and dibenzofuran. All equipment operators were assumed to be ex-
posed for the entire 8 hours of their shift since their only job function is
to operate equipment which has continual contact with the sludge, and opera-
tions are performed in open areas.
The same calculation procedures previously employed to estimate inhalation
exposure via volatilization (Equations 3 through 8) and particulate matter
generation (Equation 12) for waste treatment plant operators and sludge
haulers/front-end loader operators were used to estimate inhalation exposures
for land application equipment operators. Appendix D presents the calculation
3-43
-------
of participate emission rates (based on AP-42 emission factors), equivalent
length of the area source, and particle concentrations used in the exposure
estimations. Table 3-19 summarizes the variables used to calculate inhala-
tion exposure levels for the land application equipment operators from
volatilization of 2378 TCDD and 2378 TCDF from the wet sludge and presents
subsequent exposure estimates.
The relative toxicity of 2378 TCDF in respect to 2378 TCDD can be deter-
mined by.calculating TEQ values. In addition, the percent exposure due to
2378 TCDD can also be calculated. Using equations 9 and 10, these two vari-
ables are calculated. Table 3-20 presents the daily and lifetime average
daily TEQ and percent exposure due to 2378 TCDD from volatilization from wet
sludge for land application equipment operators. Table 3-21 presents the
assumptions and uncertainties in the variables used to calculate the daily
exposure for the land application operators from volatilization in Table
3-19.
Table 3-22 summarizes the variables for inhalation of particulate matter
generated from sludge unloading, spreading, and plowing operations at land
application sites. It presents estimated daily inhalation exposure to 2378
TCDD and 2378 TCDF for land application operators from particulate matter.
The relative toxicity of 2378 TCDF in respect to 2378 TCDD can be deter-
mined by calculating TEQ values. The percent exposure due to 2378 TCDD can
also be calculated. Equations 9 and 10 are used to calculate these two
variables. In these two equations, the daily inhalation exposure from volatil-
ization (Iv) for 2378 TCDD and 2378 TCDF is replaced with the daily exposure
from particulate matter (Ip) for 2378 TCDD and 2378 TCDF. Table 3-23
presents the daily and lifetime average daily TEQ and percent exposure due to
2378 TCDD from particulate matter for land application equipment operators.
Level of dermal exposure - Dermal exposure levels to 2378 TCDD and 2378
TCDF were based on the assumption that the equipment operators do not wear
3-44
-------
TABLE 3-19. ESTIMATED INHALATION EXPOSURE TO 2378 TCDD AND 2378 TCDF FOR
LAND APPLICATION EQUIPMENT OPERATORS FROM VOLATILIZATION
2378 TCDD
2378 TCDF
Variable
Low
High
Low
High
Reference
Henry's Law Con- 1.6x10
stant, atm-m3/mole
(He)
-5
1.6x10
-5
8.6x10
4900
-5
Soil/water parti- 1.4x10 1.4x10
tion coefficient,
mg/g in .soil per
mg/cm3 in water (Kd)
Air/soil partition 4.7xlO"10 4.7xlO"10 7.2xlO"7
coefficient,
mg/cm3 in air
per mg/g in soil
8.6x10
4900
-5
7.2x10
-7
Abt 1989
Abt 1989
Calculated
Molecular dif- 0.047
fusivity of
2378 TCDD/2378
TCDF in air,
cm2/s (Di)
Effective porosity 0.25
of soil, unit!ess
(E)
0.047
0.048
0.25
0.25
2.65
2.65
2.65
,-12
-12
1.8x10 ^ 1.8x10 iL 2.7x10
,-9
0.048
0.25
2.65
2.7x10
-9
True density of
soil g/cm3 (RHOg)
Intermediate
variable to
calculate rate
of emission from
the soil surface,
cm2/s (ALPHA)
Initial 2378 TCDD/ l.SxlO"11 7.56xlO"10 5.5xlO"U 1.39xlO"9
2378 TCDF con-
centration in
the soil on a
dry basis, g/g
Duration of ex-
posure, s (T)
Emission rate of
2378 TCDD/2378
TCDF from the
soil surface,
g/cm2-s
(continued)
2.21xl09 2.21xl09
2.21xl09 2.21xl09
8.2xlO~22 4.8xlO"2° 1.4xlO"20 3.5xlO"18
Abt 1989
Abt 1989
Abt 1989
Calculated
104-Mill
study data
Abt 1989
Calculated
3-45
-------
TABLE 3-19 (continued)
Variable
Surface area,
cm2 (A)
2378 TCDD
Low High
1.4xl07 1.4xl07
1 iwin"*" c -7,,in-l>J
2378
Low
1.4xl07
1 f\ 1 f\ ^ ^"
TCDF
High
1.4xl07
A f\ 1 f\ ^ ^
Reference
See Table 3-21
rk-»T -.. . 1 ^ 4- A J
9/5(6)
Molecular weight, 322
g/g-mole (M)
Equivalent side 37.6
length of the
area source
perpendicular
to the direction
of the wind,
m (L)
Mixing height of 1.5
the vapors
before inhala-
tion by an
individual, m
(MH)
Average windspeed 2.2
at the inhala-
tion height,
m (V)
Concentration of 9.2x10"
2378 TCDD/2378
TCDF in the
vapor, mg/m3 (Cm)
Exposure dura- 8
tion, h/day
(ED)
Daily inhala-
tion, rug/day
(Iv)
9.2xlO
"13
322
37.6
1.5
2.2
5.4x10
5.4xlO
~U
306
37.6
1.5
2.2
1.5x10
-11
306
37.6
EPA 1989c
Appendix D
1.5 EPA 1988b
2.2 EPA 1988b
3.9xlO"10 Calculated
See Table 3-21
1.5xlO"10 3.9xlO"9
Calculated
3-46
-------
TABLE 3-20. ESTIMATED TOXICITY EQUIVALENTS AND PERCENT EXPOSURE DUE
TO 2378 TCDD FOR LAND APPLICATION EQUIPMENT OPERATORS FROM VOLATILIZATION
Lifetime average
Daily TEQ, a daily TEQ,
mg/day (DTEQv)3 mg/day-kg (LTEQv)3
Low High Low HTgn
1.6X10"11 (0.6%) 4.5xlO"10 (1%) 9.2xlO"14 (0.6%) 3.0xlO"12 (1%)
a Values in parentheses are percent exposure due to 2378 TCDD.
3-47
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3-48
-------
TABLE 3-22. ESTIMATED INHALATION EXPOSURE TO 2378 TCDD AND 2378 TCDF
FOR LAND APPLICATION EQUIPMENT OPERATORS FROM PARTICULATE MATTER
2378 TCDD
Variable Low High
Concentration of 3.28 3.28
participate
matter, 'mg/m3
(Cm)3
Weight fraction l.SxlO"11 7.56xlO"10
of 2378 TCDD/
2378 TCDF in
the dry sludge,
dry basis (WF)
Exposure dura- 8 8
tion, h/day
2378 TCDF
Low High
3.28 3.28
5.5xlO~U 1.39xlO"9
8 8
Reference
Calculated
(see Appen-
dix D)
104-Mill
Study data
Engineering
judgment
(ED)
Daily inhala-
tion, mg/day
(Ip)
4.3xlO"10 2.5xlO"8
1.8x10
-9
4.6x10
-8
Calculated
a These calculations are below the OSHA nuisance dust standard of 15 mg/m3,
The exposure duration was assumed to be 8 hours since this would be the
worst-case exposure duration.
3-49
-------
TABLE 3-23. ESTIMATED TOXICITY EQUIVALENTS AND PERCENT EXPOSURE DUE TO
2378 TCDD FOR LAND APPLICATION EQUIPMENT OPERATORS FROM PARTICULATE MATTER
Lifetime average
Daily TEQ, daily TEQ,
mg/day (DTEQp)3 mg/day-kg (LTEQp)a
Low High Low High
G.lxlO"10 (19%) 2.9xlO"8 (35%) 3.4xlO"12 (19%) 2.0xlO"10 (35%)
Values in parentheses are percent exposure due to 2378 TCDD.
3-50
-------
any types of gloves that are effective in limiting exposure to PCDDs and
PCDFs. The same calculation procedure as that used to estimate dermal
exposure for waste treatment plant operators and haulers/front-end loader
operators was used to estimate dermal exposure levels for land application
equipment operators.
The 2378 TCDD and 2378 TCDF concentrations for sludge from Table 2-5 are
reported on a dry basis. Since the workers are handling wet sludge, this
concentration was adjusted to a wet basis by adjusting for the estimated
percent solids (30%) in the sludge. This corresponds to reducing the 2378
TCDD/2378 TCDF concentrations by a factor of 3.33.
Dermal exposure duration was based on engineering judgment. It was
assumed that only the palms and fingers of both hands of the equipment opera-
tor would come in contact with the wet sludge. The density of dewatered
3
sludge is 1058.8 mg/cm and a liquid film thickness for the wet sludge was
estimated to be 0.25 mm. Table 3-24 summarizes the variables and results for
dermal exposure for land application equipment operators.
The relative toxicity of 2378 TCDF in respect to 2378 TCDD can be
determined by calculating TEQ values. The percent exposure due to 2378 TCDD
can also be calculated. Equations 9 and 10 are used to calculate these two
variables. In these two equations, the daily inhalation exposure from
volatilization (Iv) for 2378 TCDD and 2378 TCDF are replaced with the daily
dermal exposure (DEW) for 2378 TCDD and 2378 TCDF. Table 3-25 presents the
daily and lifetime average daily TEQ and percent exposure due to 2378 TCDD
from dermal exposure for land application equipment operators. Table 3-26
presents the assumptions and uncertainties in the variables used to calculate
the dermal exposures for land application equipment operators in Table 3-24.
3-51
-------
TABLE 3-24. ESTIMATED DERMAL EXPOSURE TO 2378 TCDD AND 2378 TCDF
FOR LAND APPLICATION EQUIPMENT OPERATORS
2378 TCDD
2378 TCDF
Variable
Low
High
Low
High Reference
2378 TCDD/2378 TCDF 3.9
concentration of wet
sludge, wet basis,
ppt (DC)
Density of the
sludge, mg/cm3
(P)
Liquid film thick- 0.025
ness of the
sludge, cm (FT)
Bioavailability 0.15
factor for
sludge, unitless
(B)
Absorption coeffi- 0.012
cient of TCDD/TCDF
through the skin,
h"1 (AD)
Skin surface 250
area, cm2 (S)
Exposure duration,
h/day (ED)
Dermal exposure,
mg/day (DEW)
4.7x10
-11
227
1,058 1,058
0.025
0.15
0.012
300
3.2x10
-9
16.5
417 See Table 3-26
1,058 1,058 EPA 1979
0.025 0.025 See Table 3-10
0.15 0.15 EPA 1989d
0.012 0.012 EPA 1989d
250 300 See Table 3-26
1 See Table 3-26
2.0xlO"10 6.0xlO"9 Calculated
3-52
-------
TABLE 3-25. ESTIMATED TOXICITY EQUIVALENTS AND PERCENT EXPOSURE DUE
TO 2378 TCDD FOR LAND APPLICATION EQUIPMENT OPERATORS FROM DERMAL EXPOSURE
Lifetime average
Daily TEQ, daily TEQ,
. mg/day (DTEQd)3 mg/day-kg (LTEQd)a
Low High Low High
6.6xlO~U (19%) 3.8xlO"9 (35%) 3.7xlO"13 (19%) 2.6X10"11 (35%)
Values in parentheses are percent exposure due to 2378 TCDD.
3-53
-------
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3-54
-------
3.1.2.3 Distribution of Sludge as a Saleable Product--
In heat-drying operations, which are used to dry the sludge so that it
can be further processed into fertilizer, exposure to 2378 TCDD and 2378 TCDF
may occur primarily through inhalation of particles entrained in the air
during handling and conveying of the dried sludge to storage and distribu-
tion. Inhalation exposure will also occur in fertilizer manufacturing opera-
tions in which grinding, screening, and bagging of the dried sludge will
produce particulate matter emissions. Dermal exposure to 2378 TCDD and 2378
TCDF may occur at the mills through cleanup and emergency maintenance, but is
more likely in fertilizer manufacturing operations in which the sludge is
much further processed. Dermal and inhalation exposures for this type of
operation are not estimated because only one of the mills practices flash
drying.
Equipment operators may be exposed to 2378 TCDD and 2378 TCDF by inhala-
tion of particulate matter generated during composting operations. Particu-
late matter, which may be inhaled by the equipment operator, is generated
during unloading of sludge, its placement in a window or pile, mixing bulking
agents with the sludge, turning and mixing of the compost piles, removal of
compost from piles and unloading at the screening operations, loading compost
into the screens, and loading screened compost into piles and eventually into
trucks for distribution. In addition, the equipment operators may inhale
2378 TCDD and 2378 TCDF which has volatilized from the wet sludge. It is
estimated that the equipment operators may be exposed to 2378 TCDD and 2378
TCDF by inhalation throughout their 8-hour shift because their only job
function is to operate equipment which is continuously in contact with the
sludge/compost and operations are done in open areas.
3-55
-------
Dermal exposure of equipment operators to the sludge/compost is minimal.
It is estimated that the time of dermal exposure for the equipment operators
is only 1 hour per shift because they are generally not in contact with the
sludge/compost unless maintenance of the equipment is required.
The screen operators may be exposed to 2378 TCDD and 2378 TCDF via
inhalation of particulate matter generated during screening of the compost.
In addition, exposure may also occur from volatilization of 2378 TCDD and
2378 TCDF in the compost. It is estimated that the screen operators may be
exposed via inhalation throughout their 8-hour shift because their major job
function is to oversee screening operations which are generally conducted in
an open area.
Dermal exposure of screen operators to the compost occurs during routine
maintenance of the screen, such as unplugging, which occurs when the compost
is too wet, and cleaning of any spilled material. It is estimated that the
time of dermal exposure is 4 hours per shift assuming that screen cleaning
and maintenance activities involve half of the 8-hour shift of the screen
operators.
Compost haulers may be exposed to 2378 TCDD and 2378 TCDF through load-
ing and unloading of the compost from the dump truck. After the dump truck
is loaded with compost, the compost hauler transports it to farms or facil-
ities which further process the compost, and unloads it. Exposure to 2378
TCDD and 2378 TCDF may occur through inhalation of particulate matter gen-
erated during compost loading and unloading, and from volatilization of 2378
TCDD and 2378 TCDF from the compost. Dermal exposure to 2378 TCDD and 2378
TCDF occurs during maintenance activities. It is estimated that these
workers may be exposed through volatilization and inhalation of particulate
3-56
-------
matter for 4 hours per shift assuming loading and unloading activities involve
half of the work time during an 8-hour shift. The compost hauler is assumed
to spend the other half of his shift in transit. The time for dermal exposure
for the compost haulers is estimated to be 1 hour per shift, because they
will generally not be in contact with the compost unless maintenance is
required. Compost is initially wet and then dried. As a worst case exposure
assessment, the handling of dry material was used in dermal exposure calcula-
tions.
It was assumed that loading and unloading of the compost by the compost
hauler is conducted daily throughout the year. It is possible that these
operations could be seasonal, but PEI assumed, for worst-case conditions,
that the operations were performed daily.
The following is an estimation of both inhalation and dermal exposures
for equipment operators, screen operators, and compost haulers. The concen-
trations of 2378 TCDD and 2378 TCDF in sludge used in the exposure
calculations for workers in composting operations are the low and high
concentrations reported in the 104-Mill Study data for the sludges which are
disposed of by distribution as a salable product corresponding to the
calculated low and high TEQ. The mills which practice distribution of sludge
as a salable product were identified in the 104-Mill Study data provided by
EPA. Particulate matter emissions from compost handling operations were
calculated using AP-42 equations and National Emission Data System (NEDS)
emission factors, which are documented in Appendix E.
Particulate matter emissions from unloading and loading, screening, and
mixing of sludge and compost were calculated using emission factors from
3-57
-------
AP-42 (EPA 1985 and EPA 1988d) and NEDS (Stockton and Stalling 1987 and EPA
1988c). The emission factor for unloading and loading various materials is
presented in Section 11.2.3 of AP-42 (EPA 1988d). This emission factor was
used because the methodology to calculated PCDD/PCDF releases from
particulate matter presented in EPA 19885 use particulate matter emission
factors taken from AP-42 (EPA 1985 and EPA 1988d). The emission factors for
screening and mixing of sludge and compost were taken from NEDS 1or conveying
and screening of sand and aggregates. These emission factors were used as
default emission factors because none exist for compost and sludge screening
and mixing. The emissions from screening appeared to be overestimated by the
emission factor used. In this instance, the Occupational Safety and Health
Administration (OSHA) permissible exposure limit (PEL) of 15 mg/m (8-hour
time-weighted average) for nuisance dust was used for ambient particulate
concentration.
Level of inhalation exposureIn composting operations, tnere are three
job categories (equipment operators, screen operators, and compost haulers)
potentially exposed to PCDDs and PCDFs through inhalation of vapors and par-
ticulate matter containing dioxin and dibenzofuran. All equipment operators
and screen operators were assumed to be exposed for the entire 8 hours of
their shift. Compost haulers were assumed to be exposed for half of their
8-hour shift (i.e., a total of 4 hours).
The same calculation procedures previously employed to estimate inhala-
tion exposure to PCDDs and PCDFs by vaporization (using Equations 3 through
8) and particulate matter generation (using Equation 12) for waste treatment
plant operators and sludge haulers/front-end loader operators were used to
estimate inhalation exposure to equipment operators, screen operators, and
compost haulers in composting operations. Appendix E presents the calcu-
3-58
-------
lation of participate emission rates (based on AP-42 emission factors),
equivalent length of the area source, and particulate concentrations used in
the exposure estimations. Table 3-27 summarizes the variables used to
calculate inhalation exposure for the composting operation workers from
volatilization of PCDDs and PCDFs from wet sludge/compost and presents sub-
sequent exposure estimates.
The relative toxicity of 2378 TCDF in respect to 2378 TCDD can be deter-
mined by calculating TEQ values. In addition, the percent exposure due to
2378 TCDD can also be calculated. Using equations 9 and 10 these two vari-
ables are calculated. Table 3-28 presents the daily and lifetime average
daily TEQ and percent exposure due to 2378 TCDD from volatilization from wet
sludge/compost for composting operation workers. Table 3-29 presents the
assumptions and uncertainties in the variables used to calculate the daily
exposure for composting operation workers from volatilization in Table 3-27.
Table 3-30 summarizes the variables for inhalation of particulate matter
generated from sludge/compost unloading and loading, turning, mixing, and
screening operations. It presents estimated daily inhalation exposure to
2378 TCDD and 2378 TCDF for composting operation workers from particulate
matter.
The relative toxicity of 2378 TCDF with respect to 2378 TCDD can be
determined by calculating TEQ values. The percent exposure due to 2378 TCDD
can also be calculated. Equations 9 and 10 are used to calculate these two
variables. In these two equations, the daily inhalation exposure from vola-
tilization (Iv) for 2378 TCDD and 2378 TCDF are replaced with the daily
exposure from particulate matter (Ip) for 2378 TCDD and 2378 TCDF. Table
3-31 presents the daily and lifetime average daily TEQ and percent exposure
due to 2378 TCDD from particulate matter for composting operation workers.
3-59
-------
TABLE 3-27. ESTIMATED INHALATION EXPOSURE TO 2378 TCDD AND 2378 TCDF
FOR COMPOSTING OPERATION WORKERS FROM VOLATILIZATION
2378 TCDD
2378 TCDF
Variable
Low
High
Low
High
Reference
-5
1.6xlO"5 8.6x10
-5
Henry's Law Con- 1.6x10
stant, atm-m3/mole
(He)
Soil/water parti- 1.4xl06 1.4xl06 4900
tion coefficient,
mg/g in 'soil per
mg/cm3 in water (Kd)
Air/soil partition 4.7xlO"10 4.7xlO"10 7.2xlO"7
coefficient,
mg/cm3 in air
per mg/g in soil
^as*
Molecular dif- 0.047 0.047 0.048
fusivity of
2378 TCDD/2378
TCDF in air,
cm2/s (Di)
Effective porosity 0.25 0.25 0.25
of soil, unitless
(E)
8.6x10
49UO
-5
7.2x10
-7
0.048
0.25
Abt 1989
Abt 1989
Calculated
Abt 1989
Abt 1989
True density of
soil g/cm3 (RHO J
s
Intermediate
variable to
calculate rate
of emission from
the soil surface,
cm2/s (ALPHA)
Initial 2378 TCDD/
2378 TCDF con-
centration in
the soil on a dry
basis, g/g
(C
-------
TABLE 3-27 (continued)
Variable
Surface area,
cm2 (A)
- Equipment
operators
- Haulers
- Screen
2378 TCDD
Low High
6.5xl08 6.5xl08
29,729 29,729
177,600 177,600
2378 TCDF
Low High
6.5xl08 6.5xl08
29,729 29,729
177,600 177,600
Reference
See Table 3-29
See Table 3-29
See Table 3-29
-13
-18
-17
operators
Generation rate,
9/s (G)
- Equipment 1.4x10
operators
- Haulers 6.2x10
- Screen 3.7x10
operators
Molecular weight, 322
g/g-mole (M)
Equivalent side
length of the
area source
perpendicular
to the direction
of the wind,
m (L)
- Equipment 254.4
operators
- Haulers 2.44
- Screen 6
operators
Mixing height 1.5
of the vapors
before inhala-
tion by an
individual, m
(MH)
Average wind 2.2
speed at the
inhalation
height, m (V)
4.1xlO"12 6.3xlO"U
1.9xlO"}5 2.9x10"};?
iD 1.7xlO~IH
306
322
254.4
2.44
6
1.5
2.2
254.4
2.44
6
1.5
2.2
2.5xlO"9 Calculated
1.2xlO~J~ Calculated
7.0xlO"iJ Calculated
306
EPA 1989c
254.4 Appendix E
2.44 Appendix E
6 Appendix E
1.5 EPA 1988b
2.2 EPA 1988b
(continued)
3-61
-------
TABLE 3-27 (continued)
Variable
Concentration of
2378 TCDD/2378
TCDF in the
vapor, mg/m3 (Cm)
- Equipment
operators
- Haulers
- Screen
operators
Exposure dura-
tion, h/day
(ED)
- Equipment
operators
- Haulers
- Screen
operators
Daily inhala-
tion, mg/day
(Iv)
- Equipment
operators
- Haulers
- Screen
operators
2378
Low
1.6xlO"13
7.7x10"}^
1.9xlO"iD
8
4
8
-1?
1.6x10 "
3.8x10"}^
1.9xlO~iH
TCDD
High
4.9xlO"12
2.4xHT}J
5.7x10 ^
8
4
8
4.9xlO~U
1.2xlO"H
5.7xlO~iJ
2378
Low
7.5X10"11
3.6x10"}:*
8.7xlO~iJ
8
4
8
7.5X10-10
1.8x10"}?
8.7x10"^
TCDF
High
3.0xlO"9
1.4xlO~J}
3.5X10"11
8
4
8
S.OxlO"8
7.2xlO~}J
3.5xlO"1U
Reference
Calculated
Calculated
Calculated
See Table 3-29
See Table 3-29
See Table 3-29
Calculated
Calculated
Calculated
3-62
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TABLE 3-30. ESTIMATED INHALATION EXPOSURE TO 2378 TCDD AND 2378 TCDF
FOR COMPOSTING OPERATION WORKERS FROM PARTICIPATE MATTER
Variable
2378 TCDD
Low
High
2378 TCDF
Low
High
Reference
Concentration of
participate mat-
ter, mg/m3 (Cm)a
- Equipment 2.36
operators
- Haulers 0.59
- Screen oper- 15
ators
2.36
0.59
15
2.36
0.59
15
2.36
0.59
15
Amount of 2378 3.3x10
TCDD/2378 TCDF
in the dry
sludge, dry
basis (WF)
Exposure dura-
tion, h/day
(ED)
- Equipment 8
operators
- Haulers 4
- Screen 8
operators
-12
1.01x10
-10
3.9x10
-11
1.57x10
-9
8
4
8
8
4
8
8
4
8
Calculated
(see Appen-
dix E)
Calculated
(see Appen-
dix E)
OSHA PEL for
nuisance
dust
104-Mill
Study data
Engineering
judgment
Engineering
judgment0
Engineering
judgment
Daily inhalation
mg/day (Ip)
- Equipment
operators
- Haulers
- Screen
operators
»
7.8X10"11 2.4xlO"9 9.2xlO"10 3.7xlO"8 Calculated
9.7x10"}^ 3.0xlO"J° 1.2xlO"J° 4.6x10"^ Calculated
4.9xlO"lu 1.5x10 5.9xlO"y 2.4x10"' Calculated
These concentrations are below the OSHA nuisance dust standard of 15 mg/m3,
The exposure duration was assumed to be 8 hours per day since this would
be the worst case exposure duration.
c The haulers would be exposed to particulate matter during handling to the
compost. Since the haulers spend approximately half of the shift loading
and unloading compost, it was estimated the workers would be exposed to
particulate matter for 4 hours per day.
3-66
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3-67
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Level of dermal exposureDermal exposure levels to PCDDs and PCDFs was
based on the assumption that the composting operation workers do not wear any
types of gloves that are effective in limiting exposure to PCDDs and PCDFs.
The workers are potentially in contact with both wet and dry compost. As a
worst case, the workers were assumed to be handling dry compost. The same
calculation procedure as used to estimate dermal exposure for waste treatment
plant operators and haulers/front-end loader operators was used to estimate
dermal exposure levels for the workers handling dry compost.
The 2378 TCDD and 2378 TCDF concentrations for compost from Table 2-5
are reported on a dry basis. Since the workers are assumed to be handling
dry compost as a worst-case assumption, these values are used directly in
Equation 14 for estimating dermal exposure to compost operators.
Dermal exposure duration was based on engineering judgment. It was as-
sumed that only the palms and fingers of both hands of the equipment operator
and compost hauler are in contact with the dry compost, whereas it is assumed
that both the hands and forearms of the screen operator are in contact with
3
the dry compost. The density of the compost is 513.2 mg/cm and a liquid
film thickness for the compost was estimated to be 0.25 mm. Table 3-32
summarizes the variables and results for dermal exposure for composting
operation workers.
The relative toxicity of 2378 TCDF in respect to 2378 TCDD can be
determined by calculating TEQ values. The percent exposure due to 2378 TCDD
can also be calculated. Equations 9 and 10 are used to calculate these two
variables. In these two equations, the daily inhalation exposure from
volatilization (Iv) for 2378 TCDD and 2378 TCDF are replaced with the daily
dermal exposure (DED) for 2378 TCDD and 2378 TCDF. Table 3-33 presents the
daily and lifetime average daily TEQ and percent exposure due to 2378 TCDD
from dermal exposure for composting operation workers. Table 3-34 presents
3-68
-------
TABLE 3-32. ESTIMATED DERMAL EXPOSURE TO 2378 TCDD AND 2378 TCDF
FOR COMPOSTING OPERATION WORKERS
2378 TCDD
Variable Low
2378 TCDD/2378 TCDF 3.3
concentration of
dry compost, dry
basis, ppt (DC)
Density of the 513.2
compost, mg/cm3
(P)
Liquid film thick- 0.025
ness of the com-
post, cm (FT)
Bioavailability 0.01
factor for soil ,
unitless (B)
Absorption co- 0.012
efficient of
TCDD/TCDF
through the
skin, h"1 (AD)
Skin surface
area, cm2 (S)
- Equipment 250
operators
- Haulers 250
- Screen 2,600
operators
Exposure duration,
h/day (ED)
- Equipment 1
operators
- Haulers 1
- Screen 4
operators
Dermal exposure,
mg/day (DED) 12
- Equipment 1.3x10
operators ,,,
- Haulers 1.3x10
- Screen 5.3X10"-11
operators
High
101
513.2
0.025
0.01
0.012
300
300
2,600
1
1
4
4.7X10"11
4.7X10"!1
1.6xlO"y
2378 TCDF
Low High
39 1,570
513.2 513.2
0.025 0.025
0.01 0.01
0.012 0.012
250 300
250 300
2,600 2,600
1 1
1 1
4 4
1.5X10"11 7.3xlO"10
1.5xlO"Jl 7.3x10"*°
6.2xlO"1U 2.5xlO"B
Reference
104-Mill
Study data
EPA 1979
See Table 3-10
EPA 1989d
EPA 1989d
See Table 3-34
See Table 3-34
See Table 3-34
See Table 3-34
See Table 3-34
See Table 3-34
Calculated
Calculated
Calculated
3-69
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3-72
-------
the assumptions and uncertainties in the variables used to calculate the
dermal exposures for composting operation workers in Table 3-32.
3.2 PERSONAL PROTECTIVE EQUIPMENT AND CONTROLS
Use of protective equipment such as protective clothing or gloves, eye
shields, and respirators for minimizing exposure to PCDDs and PCDFs during
sludge handling and disposal operations was not mentioned in the literature.
In general, respirators are never worn during these operations; however,
their use is recommended during composting operations (EPA 1979). Protective
clothing and gloves may be worn during sampling and maintenance activities
but are only used for the prevention of soiling of employee clothes rather
than prevention of exposure to PCDDs and PCDFs by dermal contact (Fisher
1989). The gloves, however, are not effective in limiting exposures to PCDDs
and PCDFs.
Use of control equipment to minimize worker exposure to dioxins was not
mentioned in the literature. Particulate control devices such as scrubbers,
electrostatic precipitators and fabric filters are used to control particu-
late emissions from drying and incineration operations. These controls,
however, are used to meet National Ambient Air Quality Standards (NAAQS) for
particulate matter rather than to protect workers. Landfilling and compost-
ing operations may use water to control dust during dry conditions; workers
may also be supplied with respirators during such conditions (EPA 1979).
Watering may reduce particulate matter emissions by 50 percent. Control
equipment for worker protection such as hoods and enclosed operations may be
used when sludge is further processed such as in conveying, grinding, and
bagging of compost and dried sludge prior to or during fertilizer manufac-
ture. Because of the unknown extent of utilization and efficiency of any
associated control equipment, no reductions were computed for inhalation or
dermal exposure levels for PCDDs and PCDFs.
3-73
-------
SECTION 4
CONCLUSIONS AND RECOMMENDATIONS
PCDDs and PCDFs are present in primary and secondary sludges formed
during wastewater treatment operations at pulp and paper mills, thereby
resulting in a potential for worker exposure to these chemicals in the pro-
cessing and commercial use of pulp and paper mill sludge. Two studies have
quantified their presence in sludge: the 5-Mill and 104-Mill studies.
Results from the 5-Mill Study showed that concentrations in primary, second-
ary, and combined dewatered sludge ranged from 17 to 710 ppt for 2378 TCDD
and 32 to 10,900 ppt for 2378 TCDF, with the largest concentrations reported
in secondary sludge samples. Results from the 104-Mill Study showed that
concentrations corresponding to the calculated low and high TEQ in combined
dewatered sludges ranged from 0.7 to 1390 ppt for 2378 TCDD and 3.0 to 17,100
ppt for 2378 TCDF. It also showed that concentration in non-dewatered
sludges ranged from 6 to 4500 ppq for 2378 TCDD and 6 to 14,000 ppq for 2378
TCDF.
Workers involved in pulp and paper mill sludge processing and commercial
use of the sludge may be exposed to 2378 TCDD and 2378 TCDF via three major
routes: 1) dermal contact with wet or dry sludge and compost during main-
tenance of equipment and performance of job functions; 2) inhalation of
particulate matter generated by sludge and compost handling during sludge
processing, landfill ing, land application, and composting operations
involving unloading, loading, spreading, burying, or screening of the
4-1
-------
materials; and 3) inhalation of 2378 TCDD and 2378 TCDF volatilized from the
sludge and/or compost.
Although considerable data have been collected on concentrations of 2378
TCDD and 2378 TCDF for pulp, sludge, and wastewaters in the pulp and paper
industry, no inhalation or dermal exposure data for 2378 TCDD and 2378 TCDF
are currently available. This in part because of the lack of a validated
sampling and analytical method for measuring worker exposure to these chem-
icals. PEI resorted to modeling techniques based on a number of assumptions
in order to estimate inhalation and dermal exposure to 2378 TCDD and 2378
TCDF. A range (i.e., low and high values) of exposure and risk estimates are
presented for each industry/worker scenario and exposure route.
The model used in this report for estimating exposures to 2378 TCDD/2378
TCDF vapors utilizes a mass balance approach to estimate worker exposures
from an area source for specific activities. It should be noted that the
inhalation exposure estimates do not include any quantitative reductions in
volatilization of 2378 TCDD and 2378 TCDF due to binding with organic matter
and from interference due to other chemicals present in the sludge or compost
because of a lack of available data regarding these effects; thus, the inhala-
tion exposure values should be interpreted as worst-case estimates.
Data were not available on the amount of particulates generated during
sludge handling operations such as loading/unloading, spreading, compacting,
plowing into the soil, and composting. Appendices B through E present the
methodology and assumptions used in estimating the amount of particulates
generated during sludge processing/handling, landfilling operations, land
application, and composting operations; the widely used AP-42 emission
factors were utilized for these estimates. In addition, no data were avail-
able on the amount of 2378 TCDD and 2378 TCDF in the particulates; therefore,
4-2
-------
it was assumed that the concentration of 2378 TCDD and 2378 TCDF in the
sludge was equal to that in the particulates. This approach again assumes a
worst-case exposure level for 2378 TCDD and 2378 TCDF.
There were no data available on dermal exposures for workers handling
pulp and paper mill sludge. PEI estimated dermal exposure based on a CPSC
model. This model considers the partitioning of PCDD/PCDF from the
appropriate matrix (e.g., soil, sludges, paper) to a liquid (i.e., waste,
skin soil, urine, blood) and percutaneous absorption of PCDDs and PCDFs from
the liquid. This model pertains to the handling of sludge/soil. PEI assumed
worst case exposure durations when no data on the duration of exposure were
available.
Table 4-1 summarizes the 2378 TCDD and 2378 TCDF daily inhalation and
dermal exposure levels estimated in this report for workers involved in
processing and commercial usage of pulp and paper mill sludge. Table 4-2
summarizes daily toxicity equivalents, lifetime average daily toxicity equiv-
alents, and the percentage exposure due to 2378 TCDD estimated in this report
for workers involved in processing and commercial usage of pulp and paper
mill sludge. Appendix F presents the methodology for the calculation of
average and population risks for workers involved in the processing and
commercial use of pulp and paper mill sludge. Table 4-3 summarizes the
average and population risks estimated in this report based on lifetime
average daily toxicity equivalents for workers involved in processing and
commercial usage of pulp and paper mill sludge.
There are several data needs for developing more refined estimates on
worker exposure to PCDDs and PCDFs for pulp and paper mill sludge processing
and commercial use. Some areas in which additional information is needed
include the following: 1) characterization of worker activities; 2) the
4-3
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4-7
-------
TABLE 4-3. SUMMARY OF AVERAGE AND POPULATION RISKS BASED ON LIFETIME AVERAGE
DAILY TOXICITY EQUIVALENTS FOR WORKERS INVOLVED IN PROCESSING AND COMMERCIAL
USAGE OF PULP AND PAPER MILL SLUDGE
Estimated risk3
Job category
Sludge handling/processing
- Sludge haulers/front-end
loader operators
- Waste treatment plant
operators
Landfilling operations
- Equipment operators
Land application operations
- Equipment operators
Composting operations
- Equipment operators
- Compost haulers
- Screen operators
No. of
workers Exposure type
400 Inhalation-volatilization
Inhalation-particulate
matter
Dermal
1300 Inhalation-volatilization
Inhalation-particulate
matter
Dermal
400 Inhalation-volatilization
Inhalation-particulate
matter
Dermal
20 Inhalation-volatilization
I nhal ati on-parti cul ate
matter
Dermal
150 Inhalation-volatilization
Inhalation-particulate
matter
Dermal
50 Inhalation-volatilization
Inhalation-particulate
matter
Dermal
20 Inhalation-volatilization
Inhalation-particul ate
matter
Dermal
Average risk, unitless
Low
2xlO"H (0.6)
IxlO"10 (19)
6xlO"9 (19)
2xlO"12 (0.6)
2xlO"U (19)
IxlO"7 (19)
5xlO"10 (0.6)
IxlO"8 (19)
6xlO"9 (19)
-R
3x10 * (0.6)
IxlO"6 (19)
IxlO"7 (19)
IxlO"7 (0.2)
3xlO"7 (8)
4xlO"9 (8)
3xlO"10 (0.2)
3xlO"8 (8)
4xlO"9 (8)
IxlO"9 (0.2)
2xlO"6 (8)
2xlO"7 (8)
High
2xlO"7 (0.2)
5xlO"7 (8)
3xlO"5 (8)
9xlO"9 (0.2)
7xlO'8 (8)
4xlO"4 (8)
2xlO"6 (0.2)
2xlO'5 (6)
IxlO"5 (6)
9xlO"7 (1)
6xlO"5 (35)
7xlO"6 (35)
6xlO'6 (0.2)
IxlO'5 (6)
2xlO'7 (6)
IxlO'8 (0.2)
IxlO'6 (6)
2xlO"7 (6)
7xlO"8 (0.2)
7xlO"5 (6)
8xlO"6 (6)
Population risk
cases/yr
Low
8xlO"10
4xlO"9
2xlO'7
2X10"11
2X10'10
IxlO"6
5xlO"9
IxlO"7
6xlO"8
IxlO"8
5xlO"7
5xlO"8
5xlO"7
IxlO"6
2xlO'8
4xlO"10
4xlO"8
5xlO"9
7xlC"10
9xlO~7
9xlO"8
High
5xlO"6
2xlO"5
8xlO"4
9xlO"8
7xlO"7
4xlO"3
2xlO"5
2xlO"4
IxlO"4
4xlO"7
3xlO"5
4xlO"6
2xlO"5
4xlO"5
9xlO"7
2xlO"8
2xlO"6
3xlO~7
3xlO"8
4xlO"S
4xlO"6
3 Values ir parentheses are percent risk due to 2378 TCDD.
4-8
-------
number of workers in different job categories; 3) the potential for worker
exposure in the various sludge processing and disposal operations; 4) the
frequency and duration of potential dermal and inhalation exposure to PCDDs
and PCDFs from pulp and paper mill sludge processing and use; and 5) the
extent of use and effectiveness of personal protective equipment and engi-
neering controls in this industry. This information is also needed for
operations which may not be affiliated with pulp and paper mills such as
composting operations and processing of dried sludge for fertilizer manu-
facture. Most of the estimates regarding types and numbers of workers and
duration of exposure used in this report were based upon parallels with
municipal sludge-handling operations and engineering judgment.
There are some ongoing as well as planned studies which may clarify some
of the uncertainties and fill some data gaps in this report. The 104-Mill
Study has been completed; however, the data that was collected needs to be
analyzed with respect to plant operating parameters such as sludge and pulp
production rates, type of wood used (e.g., softwood, hardwood), pulping
technology used (e.g. Kraft, sulfite), and quantity of bleaching chemical
used. PEI is awaiting authorization to receive Toxic Substances Control Act
(TSCA) Confidential Business Information (CBI) in order to perform additional
analyses on data from the 104-Mill Study. The 25 Bleach Line Study by NCASI
is expected to be completed in early 1990 and will provide 2378 TCDD and 2378
TCDF concentration data for sludges in addition to effluent, bleach plant
filtrates, and intermediate and final pulps. Site visits to pulp and paper
manufacturing operations as well as to affiliated or non-affiliated
disposal or commercial sludge processing sites would also provide additional
insight on the potential for exposure to workers when performing different
activities.
4-9
-------
REFERENCES
(Abt 1989)
(Bond 1989)
(Clement 1981)
(Clement 1982)
(CPSC 1989)
(Drivas, Simmonds,
and Shair 1981)
(Eitzer and Hites
1986)
(EPA 1979)
(EPA 1984)
(EPA 1985)
Abt Associates, Inc. September 28, 1989. Multimedia
Exposure Assessment for Re-Use and Disposal of Sludge
from Pulp and Paper Industry and Disposal of Paper
Products (Final Draft). Prepared for the Office of
Pesticides and Toxic Substances of the U.S. Environmental
Protection Agency.
Personal communication between Gary Bond, NCASI and PEI
Associates, Inc. July 1989.
Clement Associates, Inc. 1981. Mathematical Models for
Estimating Workplace Concentration Levels: A Literature
Review. Prepared for the Economics and Technology Divi-
sion of the U.S. Environmental Protection Agency.
Clement Associates, Inc. 1982. Methods for Estimating
Workplace Exposure to PMN Substances. Prepared for the
Economics and Technology Division of the U.S. Environ-
mental Protection Agency.
Personal Communications between Mike Babich, Consumer
Products Safety Commission and PEI Associates, Inc. on
equations for estimating dermal exposures from wet and
dry pulp, paper, and sludges. October 1989.
Drivas, P. S., Simmonds, P. G., and Shair, F. H. 1981.
Experimental Characteristics of Ventilation Systems in
Buildings. Current Research 6:609-614.
Eitzer and Hites. 1986. Referenced in U.S.
Environmental Protection Agency Study under Consent
Agreement. 1989. Section 2.0 Chemistry and Fate of
Dioxins and Furans.
U.S. Environmental Protection Agency. 1979. Process
Design Manual for Sludge Treatment and Disposal.
EPA-625/1-79-011.
U.S. Environmental Protection Agency, Office of Health
and Environmental Assessment. 1984. Health Assessment
Document for Polychlorinated Dibenzo-p-Dioxins. Draft
Document.
U.S. Environmental Protection Agency. 1985. Compilation
of Air Pollutant Emission Factors. Fourth edition.
AP-42.
R-l
-------
REFERENCES (continued)
(EPA 1986)
(EPA 1988a)
(EPA 1988b)
(EPA 1988c)
(EPA 1988d)
(EPA 1989a)
(EPA 1989b)
(EPA 1989c)
(EPA 1989d)
(Fisher 1989)
(Hammer 1975)
(Hawks 1989)
U.S. Environmental Protection Agency. 1986. Development
of Advisory Levels for Polychlorinated Biphenyls (PCBs)
Cleanup. Office of Health and Environmental Assessments,
Washington, D.C. EPA 600/6-86-002.
U.S. Environmental Protection Agency. 1988a. U.S.
EPA/Paper Industry Cooperative Dioxin Screening Study.
EPA-440/1-88-025.
U.S. Environmental Protection Agency. 1988b. Estimating
Exposures to 2,3,7,8-TCDD. Office of Health and
Environmental Assessment. EPA/600/6-88/005A.
U.S. Environmental Protection Agency. 1988c. NEDS
Source Classification Codes and Emission Factor
Listing-PMlO. Second Edition.
U.S. Environmental Protection Agency. 1988. Supplement
B to Compilation of Air Pollution Emission Factors.
Volume I: Stationary Point and Area Sources. AP-42.
Personal communication between Jennie Helms, U.S. EPA and
PEI Associates, Inc. 1989.
Correspondence between Christina Cinalli, Environmental
Protection Agency (EPA) Exposure Assessment and George
Heath, EPA Engineering Technology Division on calculation
procedure for lifetime average daily exposures, percent
exposure due to 2378 TCDD and risk. 1989b.
U.S. Environmental Protection Agency Study under Consent
Agreement. 1989c. Section 2.0 Chemistry and Fate of
Dioxins and Furans.
U.S. Environmental Protection Agency. 1989d. Interagency
agreement between EPA, Federal Drug Administration, and
Consumer Product Safety Commission. Common Assumptions
for the Assessment of Human Dermal Exposure to
Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans.
Personal communications between Robert Fisher, NCASI and
PEI Associates. 1989.
Hammer, M.J. 1975. Water and Waste-Water Technology.
John Wiley & Sons, New York.
Personal communication between Ron Hawks and PEI Asso-
ciates, Inc. 1989.
R-2
-------
REFERENCES (continued)
(Hornung 1987)
(Hwang and Falco
1986)
(Kirk-Othmer 1981)
(Ledbetter 1976)
(Metcalf & Eddy,
1979)
(NCASI 1988)
(Olson 1988)
(Podall 1986)
(Popendorf 1982)
(Stockton and
Stelling 1987)
(Sullivan 1989)
(Thibodeaux 1979)
Hornung, R. W. and Reed, L. D. 1987. Estimation of
Average Concentrations in the Presence of Nondetectable
Values. National Institute for Occupational Safety and
Health. Cincinnati, Ohio.
Hwang and Falco. 1986. Estimation of Multimedia
Exposures Related to Hazardous Waste Facilities. In:
Cohen. Y., ed., Pollutants in a Multimedia Environment.
Plenum Publishing Co. New York, NY.
Kirk-Othmer. 1981. Encyclopedia of Chemical Technology.
3rd Ed., Vo. 16. John Wiley & Sons, New York.
Ledbetter, R.H. 1976. Design Considerations for Pulp
and Paper-Mill Sludge Landfills. EPA-600/3-76-111.
Metcalf & Eddy, Inc. 1979.
Treatment, Disposal, Reuse.
New York.
Wastewater Engineering:
McGraw-Hill Book Company,
National Council of the Paper Industry for Air and Stream
Improvement. Inc. 1988. Assessment of Potential Health
Risks to Pulp Mill Workers from Dermal Exposure to Dioxin
in Bleached Pulp, Paper, and Pulp-based Products.
Technical Bulletin No. 549. New York.
Olson, L.J., et al. 1988. Landspreading
Dioxin-Contaminated Papermill Sludge: A Complex Problem.
Archives of Environmental Health 43(2): 186-189.
Podall, et al. 1986. Referenced in U.S. Environmental
Protection Agency Study under Consent Agreement. 1989.
Section 2.0 Chemistry and Fate of Dioxins and Furans.
Popendorf, W. J. and J. T. Leffingwell. 1982. "Regula-
ting of Pesticide Residues for Farmworker Protection".
Residue Review, 82, pp. 156-157. Springer-Verlog, New
York.
Stockton, M. B. and 0. H. Stelling. 1987. Criteria
Pollutant Emission Factors for the 1985 NAPAP Emissions
Inventory. EPA-600/7-87-015.
Personal communication between Clare Sullivan, United
Paperworkers International Union and PEI Associates, Inc.
1989.
Thibodeaux, L. J.
Sons, New York.
1979. Chemodynamics. John Wiley and
R-3
-------
REFERENCES (continued)
(UPIU 1989) United Paperworkers International Union, AFL-CIO/CLC.
1989. The Dioxin Data: What Does It Mean? The
Paperworker, 17(7): 18-21.
(Versar 1984) Versar. 1984. Exposure Assessment for Retention of
Chemical Liquids on Hands. Prepared for the U.S. EPA
under Contract No. 68-01-6271.
(Wong 1983) Wong, K. 1983. Unpublished EPA report.
R-4
-------
APPENDIX A
104-MILL STUDY: 2378 TCDD AND 2378 TCDF
CONCENTRATIONS IN SLUDGE ON
A DRY BASIS
A-l
-------
Company & Location Sludge (ppt)a
2378 TCDD 2378 TCDF
Alabama River Pulp
Claibome, AL 68.0 342.0
73.0 393.0
81.0 373.0
Alaska Pulp Corp.
Sitka, AK 4.7 42.0
Appleton Papers, Inc.
Roaring Springs, PA 5.0 113.0
Badger Paper Mills, Inc. , ,
Peshtigo, WI 36.0 1800.0°
Boise Cascade Corp.
Jackson, AL 18.0 147.0
18.0. 169.0.
DeRidder, LA 280.0° 440.0°
St. Helens, OR 4.2 25.0
Rumford, ME 105.0 674.0
Wallula, WA 70.0 1490.0
International Falls, MN 24.0 380.0
37.0 680.0
710.0 10,900.0
Bowater Corp. . .
Catawba, SC 620.0° 880.0°
Calhoun, TN 4500.0° 14,000.0°
Brunswick Pulp/Paper
Brunswick, GA 33.0 62.0
Buckeye Cellulose (P&G)
Perry, FL 12.0 40.0
Oglethorpe, GA 2.6 3.0
2.6 6.1
Champion Intl. Corp.
Lufkin, TX 17.0 32.0
18.0 34.0
36.0 78.0
Courtland, AL 215.0 923.0
Quinnesec, MI 95.0 735.0
Cantonment, FL 14.0 21.0
Houston, TX 106.0 144.0
Canton, NC 172.0 260.0
A-2
-------
Company & Location Sludge (ppt)a
2378 TCDD 2378 TCDF
Chesapeake Corp.
West Point, VA 14.0 47.0
Consolidated Papers, Inc.
Wisconsin Rapids, WI 54.0 330.0
69.0 556.0
134.0 679.0
Container Corp. of America
Brewton, AL 16.0 34.0
Federal Paper Board Co. .
Augusta, GA 680.0 1400.0
Riegelwood, NC 2.9 3.3
3.8 5.2
Gaylord Container
Antioch, CA 101.0 1570.0
Georgia-Pacific Corp.
Bellingham, WA 19.0 584.0
Crossett, AR 168.0, 1680.0,
190.0? 710.0°
Palatka, FL 92.0° 410.0°
Woodland, ME 0.9 7.3
Zachary, LA (Port Hudson) 17.0 421.0
Gil man Paper Co. . ,
St. Marys, GA 220.0 610.0°
International Paper Co.
Bastrop, LA 140.0 677.0
Erie, PA 0.7C 3.0
0.9 3.1
Georgetown, SC 62.0 161.0
Jay, ME 180.0 760.0
Mobile, AL 108.0 617.0
Moss Point, MS 161.0 1020.0
Natchez, MS 14.0 78.0
Pine Bluff, AR 185.0, 2940.0,
Selma, AL 680.0 2900.0
Texarkana, TX 71.0 1000.0
86.0 387.0
Ticonderoga, NY 59.0 267.0
306.0 2470.0
A-3
-------
Company & Location
ITT-Rayonier, Inc.
Fernandina Beach, FL
Hoquiam, WA
Jesup, GA
Port Angeles, WA
James River Corp.
Berlin, NH
Camas, WA
Clatskanie, OR
Green Bay, WI
Old Town, ME
St. Francesville, LA
Butler, AL
Kimberly-Clark Corp.
Coosa Pines, AL
Leaf River Forest Products
(Great Northern Nekoosa)
New Augusta, MS
Lincoln Pulp/Paper
Lincoln, ME
Longview Fibre Co.
Long view, WA
Mead Corp.
Chillicothe, OH
Escanaba, MI
Kingsport, TN
Nekoosa Papers, Inc.
(Great Northern Nekoosa)
Ashdown, AR
Nekoosa and Port Edwards, WI
Pentair, Inc.
Park Falls, WI
Sludge
2378 TCDD
4.7
4.8
3.0
47.0
98.0
104.0
12.0
19.0
89.0
35.0
12.0
96.0
330.0°
K
3800.0°
212.0
756.0
48.0
69.0
3.3
125.0,.
1.5C
13.0
109.0
9.4
11.0
(ppt)3
2378 TCDF
32.0
25.0
2.4
65.0
2170.0
2930.0
105.0
100.0
810.0
250.0
34.0
243.0.
1100.0°
K
9200.0°
413.0
1300.0
223.0
437.0
39.0
574.0
25.0
30.0
1300.0
90.0
73.0
A-4
-------
Company & Location Sludge (ppt)a
2378 TCDD 2378 TCDF
Pope & Talbot, Inc.
Halsey, OR 31.0 106.0
Potlatch Corp.
Cloquet, MN 5.0 25.0
Lewiston, ID 78.0 639.0
McGhee, AR 91.0 433.0
P.H. Glatfelter Co.
Spring Grove, PA 93.0 238.0
Procter & Gamble Co. . ,
Mehoopany, PA 6.0 6.0
Scott Paper Co.
Hinckley, ME 6.9 29.0
33.0 106.0
39.0 149.0
67.0 330.0
Mobile, AL 9.5 18.0
Westbrook, ME 13.0 55.0
Simpson Paper Co.
Anderson, CA 278.0 6740.0
Tacoma, WA 29.0 106.0
39.0 101.0
Stone Container Corp. . .
Missoula, MT 55.0° 150.0D
Panama City, FL 3.6 16.0
Tempie-Eastex, Inc.
Evadale, TX 16.0 49.0
Union Camp Corp.
Eastover, SC 6.9 13.0
Franklin, VA 3.6 6.0
Wausau Paper Mills Co.
Brokaw, WI 3.2 68.0
4.1 56.0
A-5
-------
Company & Location Sludge (ppt)a
2378 TCDD 2378 TCDF
Westvaco Corp.
Covington, VA
Luke, MD
Wickliffe, KY
Weyerhaeuser Co.
Cosmopolis, WA
Longview, WA
New Bern, NC
Plymouth, NC
Rothschild, WI
Willamette, Ind.
Hawesville, KY
119.0
80.0
9.4
12.0
25.0
35.0
213.0
373.0
1390.0
58.0
52-°h
83.0°
799.0
471.0
46.0
61.0
80.0
89.0
1600.0
1920.0
17,100.0
150.0
h
810.0°
380.0°
NOTE: Information furnished by United States Environmental Protection
Agency, Washington, D.C., based on 104-Mill Survey; updated results
provided in computer diskette form. Concentrations reported on a dry
basis.
Concentration in ppt unless otherwise noted.
Concentrations in ppq; sludge is non-dewatered.
c Concentration of non-detectable samples was assumed to be half the
detection limit.
A-6
-------
APPENDIX B
EXPOSED POPULATION AND PARTICULATE MATTER
EMISSIONS CALCULATIONS 'FOR SLUDGE HANDLING/
PROCESSING OPERATIONS
B-l
-------
Sludge Formation/Processing
Range from 1 to 5, use average of three waste treatment personnel
104 mills bleach pulp using chlorine
3 emP]°fes x 104 mills = 312 people/shift
312 people/shift x 4 shifts = 1248 people (use 1300 people)
Sludge Handling: These personnel not included in waste treatment (sludge
formation/processing) personnel just listed.
Total sludge produced from 104-Mill Study = 2,959,152.4 tons/yr
Average sludge pr
= 78 dry tons/day
Average sludge production per mill per day (1042mins)(365 days/yr)
3
Assume: Two shifts of haulers, 5 tons of sludge per 6-yd dump truck, 1-h
round trip
78 tons/day 15.6 trips _ 15.6 h 7 R h/chift
5 tons/trip " 1 h/trip " 2 shifts " ' m° n/sniTi:
Therefore, 1 hauler/shift
Also assume one front-end loader operator/shift
Number of employees for sludge transportation = PP?Le x g-^ -
x 104 mills = 416 (use 400)
Total number of sludge-processing employees = 1300 + 400 = 1700
Convert dry tons/day to tons dewatered sludge/day = 7B dr7j°ns/day
= 260 tons/day
Particulate Emission Sources
1) Dewatered sludge loading into storage pile, 260 tons/day
2) Loading from pile into dump truck by front-end loader, 260 tons/day
,IM.3
From AP-42 Section 11.2.3 (EPA 1988d): £ = k(0.0032)V Ib/ton
30% solids.
B-2
-------
U = 8.95 mph (suggested default from EPA 1988b.)
M = 70% (moisture content of dewatered sludge)
k = 0.74 for particulate <30 ym, 0.35 for particulate <10 ym
,8.95x1.3
E = k(0.0032) { 5 ;
,70.1.2
(T>
For particulate <30 ym, k = 0.73 E = 0.000071 Ib/ton
For particulate <10 ym, k = 0.35 E = 0.000034 Ib/ton
Dewatered Sludge Loading/Unloading Emissions - Two sources
Particular <30 ym = 0.000071 Ib/ton x 260 tons/day x 2 sources
= 0.037 Ib/day
Particulate <10 ym = 0.000034 Ib/ton x 260 tons/day x 2 sources
= 0.018 Ib/day
1) Hauler/Front-End-Loader Operator
Particulate Source 2
TSP = 0.037 Ib/day * 2 sources = 0.018 Ib/day
Total particulate emissions per shift = °'018 lb/da/ = p.009 Ib
2 shifts/day shift
3 0
Outside concentration, mg/m = ,. WMU\/\M
Q = emission rate, mg/s
Q = 0.009 Ib 453.6 g 1000 mg 1 h = Q 14 ,
y 8 h x 1 Ib x g x 3600 s U<14 mg/S
L = length of treated area
MH = mixing height (suggested default from EPA 1988b = 1.5m)
V = wind speed at mixing height (suggested default from EPA 1988b
= 2.2 m/s)
3 2
Assumed surface area of 6-yd dump truck 32 ft , assume length is 2
times width.
L(0.5L) = 32
L2 = 64
L = 8 ft x 5^|2«Jn = 2.44 m
Outside concentration = (2.44 ,n)i?V2{(2.2 m/s) = °'017
B-3
-------
2} Treatment Plant Personnel
Particulate Source 1
TSP = 0.037 Ib/day * 2 sources = 0.018 Ib/day
Total particulate emissions per shift = °-018 = p.ooe
3 shifts/day shift
3 0
Outside concentration, mg/m = /. WMUW>M
n = °-006 1b x 453-6 g 1000 mg 1 h = Q m .
U 8 h x 1 Ib x g x 3600 s U'uyq mg/s
L = assume length of sludge pile 10 ft = 3 m
MH = 1.5 m (default)
V = 2.2 m/s (default)
Outside concentration, mg/m = -r-* \fi 5 mlte^ TsT = °-0095
B-4
-------
APPENDIX C
EXPOSED POPULATION AND PARTICULATE MATTER
EMISSIONS CALCULATIONS FOR LANDFILLING OPERATIONS
C-l
-------
Total sludge produced at 60 mills that landfill sludge = 1,641,416.8 dry
tons/yr
Mil average d.11, production - &*%£%? ^s
= 75.0 dry tons/day
Convert dry tons/day to dewatered tons/day (30% solids)
= 75.0 dry jons/day = ^ tops/day
From Table 19-6 of EPA 1979: Average pieces of equipment for disposal
by landfill ing 250 wet tons/day sludge
(Scheme 4) is 3
Assume each piece of equipment has its own operator.
2 overlapping shifts/day at landfill
Number of workers per landfill = °Pp^.ors x 2 shifts = 6 operators
Total number of workers = 6 operators x 60 mills that landfill sludge =
360 operators (use 400 operators)
Particulate Emission Sources
1) Dewatered sludge unloading from dump truck into landfill, 250 tons/day
2) Spreading dewatered sludge, 250 tons/day
3) Compacting dewatered sludge, 250 tons/day
4) Cover with excavated soil - No dioxin particulate from this source
Unloading Operations
From AP-42 Section 11.2.3 (EPA 1988d):
,ua.3
E = k(0.0032) ^ _ Ib/ton
U = 8.95 mph (default)
M = 70% moisture
k = 0.74 for particulate <30 pm, 0.35 for PM-10 (particulate <10
,8.95x1.3
E = k(0.0032) v 5 ;
,70x1.2
(2 '
C-2
-------
For particulate <30 ym, k = 0.74 E = 0.000071 Ib/ton
For particulate <10 ym, k = 0.35 E = 0.000034 Ib/ton
Unloading Emissions
Particulate <30 ym = 0.000071 Ib/ton x 250 tons/day = 0.018 Ib/day
Particulate <10 ym = 0.000034 Ib/ton x 250 tons/day = 0.0085 Ib/day
Spreading and Compacting
From EPA 1988b: Spreading assumed similar to agricultural tilling.
Assume both spreading and compacting similar to agricultural tilling.
From AP-42 Section 11.2.2:
E = k(48)(S)°'6 Ib/acre
k = 1 for TSP, 0.33 for <30 ym, 0.21 for <10 ym
S =.silt content of soil, in this case dewatered sludge
Assume all solids (30% in dewatered sludge) are fine particles,
thus S = 30%.
Determine daily acreage of sludge application. Dewatered sludge specif-
ic gravity =1.06 (from Hammer 1975).
250 tons v 2000 Ib .. , 1 ft3
X
day A ton A V62.4 Ib A 1.06' A
Sludge application rate - from EPA 1979, Table 19-3. Dry sludge applica-
tion rate approximately 5700 yd3/acre.
280 yd3 sludge 1 acre n nc ..
* day 9 x 5700 yd3 sludge = °'05 acres/day
Spreading and Compacting Emissions
E = k(4.8)(30)°'6 Ib/acre
For Total Suspended Particulates (TSP), k = 1 E = 36.9 Ib/acre
For particulate <30 ym, k = 0.33 E = 12.2 Ib/acre
For PM-10, k = 0.21 E = 7.76 Ib/acre
Spreading Emissions
TSP = 36.9 Ib/acre x 0.05 acre/day = 1.84 Ib/day
Particulate <30 ym = 12.2 Ib/acre x 0.05 acre/day = 0.61 Ib/day
PM-10 = 7.76 Ib/acre x 0.05 acre/day = 0.39 Ib/day
C-3
-------
Compacting Emissions
Same as spreading
TSP =1.84 Ib/day
Participate <30 ym = 0.61 Ib/day
PM-10 =0.39 Ib/day
Total participate emissions per shift = °'01Vshifts+ ^^
= 1.85 lb/8-h shift
Outside concentration, mg/m = / 1 w MU w \A
where Q = emission rate, mg/s
L = length of one side of treated area, m
MH = mixing height (assumed to be 1.5 m from EPA 1988b)
V = wind speed at mixing height (assumed to be 2.2 m/s from EPA 1988b)
0 = 1.85 1b 453.6 g 1000 mg 1 h = ^ l ,
4 8 h x 1 1b x g x 3600 s *y>1 mg/S
L. = assume application area (0.05 acre) is square
2
L = 0.05 acre x 43>6° ft2 = 2178 ft2
L = 46.7 ft x = 14.2 m
Outside concentration = (14.2 mHlsH^Z m/s) = °'62
C-4
-------
APPENDIX D
EXPOSED POPULATION AND PARTICULATE MATTER
EMISSIONS CALCULATIONS FOR
LAND APPLICATION OF SLUDGE
D-l
-------
Total sludge produced at seven mills that practice land application of sludge
= 160,582.5 dry tons/yr
Mil, average daily sludge production -
= 62.8 dry tons/yr
Convert dry tons/day to dewatered tons/day (30% solids)
62.8 dry^ons/day =
Number of workers: assume 1 shift
1 person to spread
1 person to till
Total number of workers exposed = x 1 shift x 7 mills = 14
(use 20)
Particulate Emission Sources
1) Dewatered sludge unloading from dump truck onto land, 209.5 tons/day
2) Spreading dewatered sludge, 209.5 tons/day
3) Plowing dewatered sludge into soil, 209.5 tons/day
Unloading Operations
From AP-42 Section 11.2.3 (EPA 1988d):
,Ux 1.3
E = k(0.0032) V Ib/ton
,Mjl.2
(2>
U = 8.95 mph (default)
M = 70% moisture
k = 0.74 for particulate <30 ym; 0.35 for PM-10
For particulate <30 ym, E = 0.000071 Ib/ton
For particulate <10 ym, E = 0.000034 Ib/ton
Unloading Emissions
Particulate <30 ym = 0.000071 Ib/ton x 209.5 tons/day = 0.015 Ib/day
Particulate <10 ym = 0.000034 Ib/ton x 209.5 tons/day = 0.0071 Ib/day
Spreading and Plowing
From EPA 1988b: Spreading assumed similar to tilling, plowing is same as
till ing.
D-2
-------
From AP-42 Section 11.2.2:
E = k(4.8)(S)°'6 Ib/acre
k = 1 for TSP, 0.33 for <30 ym, 0.21 for PM-10
S = silt content of soil; in this case, assume equal to solids content
of dewatered sludge - 30%
Determine daily average of sludge appliation.
Dewatered sludge specific gravity = 1.06, from Hammer 1975
Depth of application average of 5 in. from Table 19-11 of EPA 1979
. 209.5 tons 2000 1b , 1 ft* _l_, = em -j f 3
x ton x 162.4 Ib x 1.06' DJJ£f-/ TT-
6334'7 Tft = 15«203-2 ft2 x 43|56oft2 = °'35 acre/day
5 in' x 12 in.
Spreading and Plowing Emissions
E = k(4.8)(30)0'6 Ib/acre
For TSP, k = 1 E = 36.9 Ib/acre
For particulate <30 ym, k = 0.33 E = 12.2 Ib/acre
For PM-10, k = 0.21 E = 7.76 Ib/acre
Spreading Emissions
TSP = 36.9 Ib/acre x 0.35 acre/day = 12.9 Ib/day
Particulate <30 ym = 12.2 Ib/acre x 0.35 acre/day = 4.27 Ib/day
PM-10 = 7.76 Ib/acre x 0.35 acre/day = 2.72 Ib/day
Plowing Emissions
Same as spreading
TSP = 12.9 Ib/day
Particulate <30 ym = 4.27 Ib/day
PM-10 =2.72 Ib/day
Total particulate emissions = 0.015 + 12.9 + 12.9 = 25.9 Ib/day
n
Outside concentration (mg/m3) =
(UTMHTTV)
MH = 1.5 m (default)
V = 2.2 m/s (default)
= 25.8 Ib 453.6 q 1000 mg 1 h = 4Q6 4 ,
8 h x 1 Ib x g x 3600 s 4Ub'4 mg/s
D-3
-------
L = assume application area (0.35 acre/day) is square
L2 = (0.35 acre x S = 15,246 ft"
acre
L = 123.5 ft x w-°^" '" = 37.6 m
406 4 FTid/s
Outside concentration, mg/m3 = /,7 5 mHl's m)(2 2 m/s) = ^-^8 m9/m3
D-4
-------
APPENDIX E
EXPOSED POPULATIONS AND PARTICULATE MATTER
EMISSIONS CALCULATIONS FOR COMPOSTING OPERATIONS
E-l
-------
Total sludge produced at the seven mills which distribute and market sludge
205,636 dry tons/yr
Mill average d.1!y sludge production .
=80.5 dry tons/day
From EPA 1979, composting operation processing
80 to 120 dry tons/day employed 20 operators and mechanics (excluding
sludge haulers).
Outside company, however, handled compost; therefore add screening
personnel and haulers of dried compost.
Hauling: Screened compost density 865 lb/yd3, assume 6-yd3 dump truck
865 lb/yd3 x 6 yd3 x 2Q0o°"b = 2.6 tons compost/load
Convert 80.5 dry tons/day to tons/day shipped compost (60% solids)
= 134.2 tons/day compost
134.2 tons/day = .
2.6 tons/load ps
Assume 1 h round trip ->- 52 trips x 1 h = 6.5 haulers
8-h shift 8 h/shift(use 7 haulers)
8 h/day operation
Screening: Assume 2 operators
Total Population Exposed
Operators and mechanics 20 x 7 = 140 Use 150
Haulers of dried, screened sludge 7x7= 49 Use 50
Screening operators 2x7= 14 Use 20
182 220
220 people exposed who work 1 shift/day
Particulate Emission Sources
1) Unloading dewatered sludge from dump truck
2) Loading into front-end loader (PEL) and dumping into windrow/pile
3) Mixing bulking agent and dewatered sludge
4) Turning and mixing of compost piles (assume daily)
5) Removing piles and unloading at screening operations into piles by PEL
6) Removal from storage pile by PEL and placement in screens (dried com-
post)
7) Screening of compost
8) Loading of screened compost into piles for distribution
9) Unloading from pile by PEL and loading into dump truck
10) Unloading from dump truck onto farmland
E-2
-------
Unloading and Loading Operations
From AP-42 Section 11.2.3 (EPA 1988d):
,IK 1.3
E = k(0.0032) 15; Ib/ton
,M)1.2
(2)
E = emission factor, Ib/ton
k = particle size multiplier; 0.74 for <30 ym; 0.35 for <10 ym
U = mean wind speed, mph
M = material moisture content, %
Assume mean wind speed of 4 m/s = 8.95 mph (default from EPA 1988b)
Moisture content dewatered sludge = 70%
Finished compost moisture content = 55% (prior to drying) from EPA
430/9-81-001 Composting Processes to Stabilize and Disinfect
Municipal Sewage Sludge, p. 29.
Dried compost moisture content = 40% from EPA 1979
Emission Factor for Unloading/Loading Dewatered Sludge
/8.95_\1.3 Converting dry tons/day to tons dewatered
E = k(0.0032) { 5 ; sludge/day (30% solids)
^1.2 80.5 tons/day , ^ tons/day
For particulate <30 ym, k = 0.74 E = 0.000071 Ib/ton
For particulate <10 ym, k = 0.35 E = 0.000045 Ib/ton
Emission Factor for Unloading/Loading Finished Compost
/8.95>1.3 Converting dry tons/day to finished com-
E = k(0.0032) ( 5 ; post, tons/day (45% solids)
For particulate <30 ym, k = 0.74 E = 0.000095 Ib/ton
For particulate <10 ym, k = 0.35 E = 0.000045 Ib/ton
Emission Factor for Unloading/Loading Dried Compost
/8.95x1.3 Converting dry tons/day to final dried
E = k(0.0032) { 5 ; compost, tons/day (60% solids)
(40)1.2 80.5 tons/day = m^2 tQns/day
For particulate <30 ym, k = 0.74 E = 0.00014 Ib/ton
For particulate <10 ym, k = 0.35 E = 0.000066 Ib/ton
E-3
-------
Dewatered Sludge Unloading/Loading Emissions
1) Unloading from dump truck, 268.3 tons/day
2) Loading onto pile by PEL, 268.3 tons/day
Particulate <30 ym = 0.000071 Ib/ton x (2 sources x 268.3 tons/day) =
0.038 Ib/day
Particulate <10 ym = 0.000034 Ib/ton x (2 sources x 268.3 tons/day) =
0.018 Ib/day
Finished Compost Unloading/Loading Emissions
5) Removing piles and unloading at screening oporations prior to drying
17&.9 tons/day
Particulate <30 ym = 0.000095 Ib/ton x 178.9 tons/day = 0.017 Ib/day
Particulate <10 ym = 0.000045 Ib/ton x 178.9 tons/day = 0.0081 Ib/day
Dried Compost Unloading/Loading Emissions
6) Removal from storage piles after drying and placement in screens,
134.2 tons/day
8) Loading of screened compost into piles for distribution, 134.2 tons/day
9) Unloading from pile by PEL and loading into dump truck, 134.2 tons/day
10) Unloading from dump truck onto farmland, 134.2 tons/day
Particulate <30 ym = 0.00014 Ib/ton x (4 sources x 134.2 tons/day) =
0.075 Ib/day
Particulate <10 ym = 0.000066 Ib/ton x (4 sources x 134.2 tons/day) =
0.035 Ib/day
Screening Operation
7) Screening of compost, 178.9 tons/day
Use PM-10 emission factor from NEDS for SCC Code 3-05-025-11, Sand/Gravel
Screening
PM-10 emission factor: 0.12 Ib/ton
PM-10 = 0.12 Ib/ton x 178.9 tons/day = 21.5 Ib/day
For TSP, use AP-42 Appendix C.2, Table C.2-2, Category 3
51% <10 ym
TSP = = 42.1 Ib/day
Mixing and Turning Operations
3) Mixing bulking agent and dewatered sludge, 268.3 tons/day
4) Turning and mixing of compost piles, 268.3 tons/day
E-4
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Use TSP emission factor from NEDS for SCO Code 3-05-025-03, Sand/Gravel
Material Transfer and Conveying
TSP emission factor: 0.029 "Ib/ton
For PM-10 use AP-42 Appendix C.2, Table C.2-2, Category 3
PM-10 51% <10 ym
TSP = 0.089 Ib/ton x (2 sources x 268.3 tons/day) = 15.6 Ib/day
PM-10 = 0.51(15.6 Ib/day) = 7.94 Ib/day
Controls: Watering of piles during dusty conditions will reduce
particulate emissions by approximately 50%.
Total Particulate Emissions
1) Screening Operators - Screening operations (Source 7) TSP = 42.1 Ib/day
(8-h shift)
42.1 Ib 453.6 g 1000 mg 1 h = 663 l .
8 h x 1 Ib x g x 3600 s OOJ'1 mg/s
Outside concentration (mg/m3) = 0 U MH 1 f \M
MH = 1.5 m (default)
V = 2.2 m/s (default)
Q = 663.1 mg/s
L = from Kirk-Othmer 1981 - Supplement Volume, length-to-width ratio of
screen is 2:1; largest screen area is 17.76 m2
Screen area = 17.76 m2 = L (0.5L)
35.52 = L2
5.96 = L
6 m = L
Outside concentration (mg/m3) = (6 ^l.'tz m/s) = 33'5 mg/m3
2) Equipment Operators
Particulate Sources 1 through 6, 8, and 9
TSP Sources 1 and 2 = 0.038 Ib/day
Sources 3 and 4 = 15.6 Ib/day
Source 5 = 0.017 Ib/day
Sources 6, 8, 9 = 0.056 Ib/day
Total = 15.7 Ib/day (8-h shift)
15.7 Ib 453.6 g 1000 mg 1 h _ Iq7fi ? ,
8 h x 1 Ib x 1 g x 3600~? " 1978'2 mg/s
E-5
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Outside concentration (mg/m3) =
MH = 1.5 m (default)
V = 2.2 m/s (default)
Q = 1978.2 mg/s
L = assume area is square
Area assumed to be 16 acres based on EPA 1979, p. 12-24 cites
actual composting area is 1 acre per 5 dry tons of sludge. Average
dry tons/day handled is 80.5 dry tons. Dividing by 5 gives 16
acres.
I2 = 16 acres x 43'56° ft* = 696,960 ft*
acre
L = 834.8 ft x 0.3048JH =
Outside concentration (mg/m3) = (254.4 (d iffll.Z m/s) = 2'36
3) Compost Haulers
Particulate Sources 9 and 10
TSP Sources 9 and 10 = 0.038 Ib/day (8-h shift)
0.038 Ib 453.6 g 1000 mg 1 h _ . ?q .
8 h x 1 Ib x 1 g x 3600 s " 4>/y m9/s
Outside concentration (mg/m3) = /, iiM[j
Q = 4.79 mg/s
MH = 1.5 m (default)
V = 2.2 m/s (default)
L = assume length of dump truck container is 2 x width and
assume surface area of 6-yd3 dump truck is 32 ft2
L (0.5L) = 32
L2 = 64
L = 8 ft x °'i°ft m = 2.44 m
Outside concentration = (2.44 m)(K5 3(2.2 m/s) = °'59
E-6
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APPENDIX F
RISK ASSESSMENT METHODOLOGY
F-l
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RISK ASSESSMENT
This section presents the methodology for the calculation of risk to
2378 TCDD and 2378 TCDF. Unit risk is used to compare the relative potencies
of carcinogens. Potency is defined as the linear portion of a given dose-
response curve which is used to calculate the unit risk factors. On a curve,
the upper confidence limit for the extra risk calculated at low doses is
always linear. The slope (q*) is taken as the upper-bound of the potency of
the chemical (TCDD) in inducing cancer at low doses. The 95% upper confi-
dence limit of dose-response functions for the linear slope factor q* of 2378
TCDD is 0.156 kg-d/ng or 1.56 x 10+5 (mg/kg/day)'1. The derivation of this
factor is described in EPA 1984.
During the development of the slope factor an absorption factor of 55
percent was applied. The equation for calculation of average risk and popula-
tion risk are presented in Equations F-l and F-2, respectively.
AVGRISK = LTEQ x PF / AF Equation F-l
POPRISK = AVGRISK x POP / YEAR Equation F-2
Where:
AVGRISK = average risk for the lifetime average daily toxicity
equivalents, unitless
LTEQ = lifetime average daily TEQ, mg/day-kg
PF = potency factor, kg-day/mg
AF = absorption factor, unitless
F-2
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POPRISK = population risk for the lifetime average daily toxicity
equivalents, cases/year
POP = number of workers in the population
YEAR = number of years in a lifetime, years
The lifetime average daily toxicity equivalents (TEQ) which were used in
Equation F-l were presented in tables from Section 3. Three types of life-
time average daily TEQ were calculated in Section 3 for inhalation exposure
from volatilization, inhalation exposure from particulate matter, and dermal
exposure. The potency factor used in the equation was 0.156 kg-day/ng (EPA
1984). The absorption factor (AF) was estimated to be 0.55 (Farland 1987).
Table F-l summarizes the variables for the estimated average risk and
population risk for workers involved in sludge handling/processing, landfill-
ing, land application, and composting operations. The average risk and
population risks are summarized in Table 4-3. The following is an example
calculation for calculating average risk and population risk.
Lower limit for average risk for haulers/front-end loader operators han-
dling/processing sludge from volatilization
AVGRISK = 8.2xlO"17 mg/day-kg x 1.56xl05 day/kg-mg /0.55
= 2x10"U
Lower limit for population risk for haulers/front-end loader operators han-
dling/processing sludge from volatilization
POPRISK = ZxlO"11 x 1300 workers/40 years
= 8x10 cases/year
F-3
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TABLE F-l. VARIABLES FOR ESTIMATING AVERAGE RISKS
AND POPULATION RISKS
Variable
Value
Reference
Potency factor,
kg-day/mg (PF)
Absorption factor,
unitless (AF)
1.56x10
0.55
+5
EPA 1984
EPA 1988b
F-4
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0272-101
REPORT DOCUMENTATION A REPORT NO. | 2.
PAGE EPA 560/4-90-016 |
. THIe and Subtitle
Estimated Worker Exposure to 2378 TCDD and 2378 TCDF from
Processing and Commercial Use of Pulp and Paper Mill Sludge.
'. Authors)
PEI Associates, Inc.
1. Performing Organization Name and Address
PEI Associates, Inc.
11499 Chester Road
Cincinnati, OH 45246:
12. Sponsoring Organization Name and Address
U.S. Environmental Protection Agency
Office of Toxic Substances
401 M Street, S.W.
Washington, DC 20460
3. Recipient's Accession No.
*" fylft 2990
6.
8. Performing Organization Rept. No.
10. Proiect/Task/Work Unit No.
11. Contract(C) or Grant(G) No.
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