inhalation dose assessment: risk assessment of airborne particulates to workers in the phosphate ...

225 Pages·2005·5.59 MB·English

by  Academic Technology

INHALATION DOSE ASSESSMENT: RISK ASSESSMENT OF AIRBORNE
PARTICULATES TO WORKERS IN THE FLORIDA PHOSPHATE INDUSTRY

By

KWANG PYO KIM

A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA

2005
Copyright 2005

by

Kwang Pyo Kim
This document is dedicated to Dr. William Emmett Bolch who passed away on December
26, 2003.
ACKNOWLEDGMENTS
The study could not have been accomplished without the valuable assistance of
many individuals. Here, I want to acknowledge those people once more.
I would like to express my deep appreciation to my advisor, Dr. Wesley E. Bolch,
who not only guided and supported me as my advisor but also encouraged and challenged
me throughout my academic program. I appreciate the opportunity that he has provided
me to study at University of Florida and pursue my interest in health physics. I wish to
express my gratitude to Dr. Chang-Yu Wu. He provided me expertise and direction to
complete this study. Great appreciation should go to Dr. William Emmett Bolch, who
passed away on December 26, 2003. His long experience and wide and deep knowledge
in the field of environmental physics led me to successful completion of this study. My
thanks also go to my committee members, Dr. David E. Hintenlang and Dr. Guenther
Hochhaus, for reading this dissertation and providing many valuable comments that
improved this study.
This work was supported by Grant #00-05-062R and #03-05-064 from The Florida
Institute of Phosphate Research (FIPR) to the University of Florida. Dr. Brian K. Birky,
Research Director for Public Health, was very supportive of this research, and his
guidance and advice were important for its successful completion.
Many samplings were made in different plants and areas to obtain site-specific air
sampling data. This activity was greatly facilitated by many individuals: Allan Pratt,
Michael Messina, and Robert Sellers in CF industries, Debra Waters, Ryan Richards,
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Melody R. Foley, Tara Crews, Taylor D. Abel, Nelson Singletary, Santino Provenzano,
and Flint Barnes in Mosaic Company, Martin St. John and Dennis Killebrew in PCS
Phosphate, and Ron Brunk and Foster Thorpe in US Agri-Chemicals. They provided me
safety training, escort, and valuable information. Wesley Nall, Tom McNally, and
Robert Ammons in Health Unit in Winter Haven, Florida, conducted pre-sampling. Their
efforts are greatly appreciated.
Many thanks go out to all of my colleagues at the Department of Nuclear and
Radiological Engineering, especially Dr. Chulhaeng Huh, Dr. Choonsik Lee, Dr.
Eunyoung Han, Choonik Lee, Hosang Jin, and Heeteak Chung for their help and
friendship. Yu-Mei Hsu at Departments of Environmental Engineering Sciences
instructed me in the use of ion chromatography and helped its operation. I also wish to
acknowledge the help of department faculty and staff in Nuclear and Radiological
Engineering.
I thank my and my wife’s parents and family for their support. My mother
deserves to have my respect and love. She gave love, unconditional support, and
encouragement for me to live right. Last, I would like to thank my wife for her
understanding, patience, and love.

v
TABLE OF CONTENTS

page
U
ACKNOWLEDGMENTS.................................................................................................iv
T T
LIST OF TABLES.............................................................................................................ix
T T
LIST OF FIGURES..........................................................................................................xii
T T
ABSTRACT.....................................................................................................................xiv
T T T
CHAPTER
1 INTRODUCTION...................................................................................................1
1.1 Objective......................................................................................................1
1.1.1 Source and Magnitude of Problem..................................................1
1.1.2 Review of Pertinent Literature and Related Work...........................2
1.1.3 Specific Goals..................................................................................3
1.1.4 Impact of Goals................................................................................3
1.2 Methodology................................................................................................4
1.2.1 Task 1: Particle Characterization.....................................................4
1.2.2 Task 2: Effective Dose Scaling Factors...........................................5
1.2.3 Task 3: Dose Assessment via Characterization of Particle Size
Distribution......................................................................................6
1.2.4 Task 4: Particle Solubility in Lung Fluid.........................................7
1.2.5 Task 5: Risk Assessment to Workers...............................................7
2 CHARACTERIZATION OF RADIOACTIVE AEROSOLS IN FLORIDA
PHOSPHATE PROCESSING FACILITIES.........................................................11
2.1 Introduction................................................................................................11
2.2 Materials and Methods...............................................................................15
2.2.1 Dose Sensitivity to Aerosol Parameters.........................................15
2.2.2 Particle Size Distribution...............................................................16
2.2.3 Particle Density, Shape and Elemental Composition....................18
2.2.4 Particle Radioactivity.....................................................................19
2.3 Results and Discussion..............................................................................20
2.3.1 Dose Sensitivity to Particle Properties...........................................20
2.3.2 Particle Size Distribution...............................................................22
2.3.3 Particle Density, Shape, and Elemental Composition...................25
vi
2.3.4 Particle Radioactivity.....................................................................28
2.4 Conclusions................................................................................................30
3 EFFECTIVE DOSE SCALING FACTORS FOR USE WITH CASCADE
IMPACTOR SAMPLING DATA IN TENORM INHALATION EXPOSURES45
3.1 Introduction................................................................................................45
3.2 Materials and Methods...............................................................................48
3.2.1 Cutoff Size of the Cascade Impactor.............................................48
3.2.2 Other Particle Properties................................................................49
3.2.3 Radioactivity Distribution within a Sub-stage...............................50
3.2.4 TENORM Radionuclides...............................................................51
3.2.5 Dose Calculation............................................................................52
3.3 Results and Discussion..............................................................................54
3.3.1 Inhalation Dose Coefficients – Variation as a Function of
Particle Size...................................................................................54
3.3.2 Effective Dose Scaling Factors for Uniform Distributions............57
3.3.3 Effective Dose Scaling Factors for Linear Distributions...............59
3.3.4 Applications of Effective Dose Scaling Factor to Measured
Cascade Impactor Data..................................................................61
3.4 Conclusions................................................................................................63
4 EFFECTIVE DOSE SCALING FACTORS FOR USE WITH CASCADE
IMPACTOR SAMPLING DATA IN EXPOSURES TO URANIUM SERIES
(APPLICATION TO IMBA PROGRAM)............................................................87
4.1 Introduction................................................................................................87
4.2 Materials and Methods...............................................................................88
4.3 Results and Discussion..............................................................................89
4.3.1 Inhalation Dose Coefficients..........................................................89
4.3.2 Comparison of Inhalation Dose Coefficients from IMBA and
LUDEP...........................................................................................91
4.3.3 Effective Dose Scaling Factors......................................................93
4.4 Conclusions................................................................................................94
5 INFLUENCE OF PARTICLE SIZE DISTRIBUTION ON INHALATION
DOSES TO WORKERS IN THE FLORIDA PHOSPHATE INDUSTRY........108
5.1 Introduction..............................................................................................108
5.2 Materials and Methods.............................................................................109
5.2.1 Inhalation Dose Coefficients........................................................110
5.2.2 Inhalation Effective Doses to Workers........................................112
5.3 Results and Discussion............................................................................114
5.3.1 Inhalation Dose Coefficients........................................................114
5.3.2 Inhalation Effective Dose to Workers..........................................118
5.4 Conclusions..............................................................................................121
vii
6 DETERMINATION OF LUNG SOLUBILITY OF RADIONUCLIDES IN
PARTICLES IN FLORIDA PHOSPHATE PROCESSING FACILITIES.........137
6.1 Introduction..............................................................................................137
6.2 Materials and Methods.............................................................................141
6.2.1 Dose Sensitivity to Radionuclide Solubility................................141
6.2.2 Tested Samples............................................................................141
6.2.3 In vitro Solubility Test................................................................142
6.2.4 Solubility of Surrounding Material..............................................143
6.2.5 Solubility of Uranium, Thorium, and Lead.................................144
6.2.6 Data Analysis...............................................................................145
6.3 Results and Discussion............................................................................147
6.3.1 Dose Sensitivity to Radionuclide Solubility................................147
6.3.2 Lung Solubility of Particles.........................................................148
6.4 Conclusions..............................................................................................151
7 RISK ASSESSMENT OF AIRBORNE PARTICULATES TO WORKERS IN
THE FLORIDA PHOSPHATE INDUSTRY......................................................160
7.1 Introduction..............................................................................................160
7.2 Materials and Methods.............................................................................161
7.3 Results and Discussion............................................................................162
7.4 Conclusions..............................................................................................164
8 CONCLUSIONS AND RECOMMENDATIONS..............................................170
8.1 Conclusions..............................................................................................170
8.2 Recommendations....................................................................................174

APPENDIX
A PARTICLE SAMPLING AND RADIOACTIVITY DATA USED FOR DOSE
ASSESSMENT....................................................................................................175
B EFFECTIVE DOSE SCALING FACTORS APPLICABLE TO PARTICLES
IN THE FLORIDA PHOSPHATE CHEMICAL PLANTS................................195
LIST OF REFERENCES.................................................................................................201
BIOGRAPHICAL SKETCH...........................................................................................210

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LIST OF TABLES
Table page
U U U U

2-1 ICRP 66 HRTM default aerosol parameters and input aerosol parameters for
dose sensitivity study...............................................................................................32
2-2 Active operational systems and ventilation conditions during airborne particle
sampling at the various storage areas.......................................................................33
2-3 Mass density of bulk products, settled particles, and airborne particles..................34
2-4 Composition information for dry product ingredients.............................................35
2-5 Phosphorus, silicon, and sulfur composition in different sized particles.................36
2-6 238U, 226Ra, and 210Pb radioactivity concentrations in bulk dry products, settled
P P P P P P
particles, and airborne particles................................................................................37
3-1 Particle size information for each impactor stage of the University of
Washington Mark III cascade impactor...................................................................65
3-2 Reference physiological parameter values for reference worker.............................66
3-3 GI tract absorption factors (f ) for uranium series elements....................................67
1
B B
3-4 LUDEP decay-chain option for each radionuclide..................................................68
3-5 Inhalation effective dose scaling factors (SF ) for a uniform activity distribution..69
E
B B
3-6 Inhalation effective dose scaling factors (SF ) for a linearly decreasing activity
E
B B
distribution (AR of 2:1)............................................................................................70
3-7 Inhalation effective dose scaling factors (SF ) for a linearly decreasing activity
E
B B
distribution (AR of 5:1)............................................................................................71
3-8 Inhalation effective dose scaling factors (SF ) for a linearly increasing activity
E
B B
distribution (AR of 1:2)............................................................................................72
3-9 Inhalation effective dose scaling factors (SF ) for a linearly increasing activity
E
B B
distribution (AR of 1:5)............................................................................................73
ix
3-10 Example inhalation dose assessment under the assumption of mono-size,
uniform, or linearly changing radioactivity distribution per impactor stage............74
4-1 Inhalation effective dose scaling factors (SF ) for a uniform activity distribution..96
E
B B
4-2 Inhalation effective dose scaling factors (SF ) for a linearly decreasing activity
E
B B
distribution (AR of 2:1)............................................................................................97
4-3 Inhalation effective dose scaling factors (SF ) for a linearly decreasing activity
E
B B
distribution (AR of 5:1)............................................................................................98
4-4 Inhalation effective dose scaling factors (SF ) for a linearly increasing activity
E
B B
distribution (AR of 1:2)............................................................................................99
4-5 Inhalation effective dose scaling factors (SF ) for a linearly increasing activity
E
B B
distribution (AR of 1:5)..........................................................................................100
6-1 Samples employed for solubility test.....................................................................153
6-2 Composition of serum ultrafiltrate simulant..........................................................154
6-3 Retention fitting data of 238U, 232Th, and 208Pb in serum ultrafiltrate as a function
P P P P P P
of time....................................................................................................................155
7-1 Inhalation effective dose scaling factors (SF ) applicable to particles in the
E
B B
Florida phosphate chemical plants.........................................................................166
7-2 Dose rate and annual inhalation dose to workers in the Florida phosphate
chemical plants due to particle inhalation..............................................................168
7-3 Occupancy times for workers at dry product, shipping, and storage areas in the
Florida phosphate chemical plants.........................................................................169
A-1 Particle size distribution and radionuclide concentration (Granulator area)..........177
A-2 Particle size distribution and radionuclide concentration (Storage area)...............184
A-3 Particle size distribution and radionuclide concentration (Shipping area).............190
B-1 Effective dose scaling factors (SF ) applicable to particles in the Florida
E
B B
phosphate chemical plants for uniform radioactivity distribution.........................196
B-2 Effective dose scaling factors (SF ) applicable to particles in the Florida
E
B B
phosphate chemical plants for linearly decreasing radioactivity distribution (AR
= 2:1)......................................................................................................................197
B-3 Effective dose scaling factors (SF ) applicable to particles in the Florida
E
B B
phosphate chemical plants for linearly decreasing radioactivity distribution (AR
= 5:1)......................................................................................................................198
x